Please refer to the attached files.

The "Style" gallery is reinitialized each time the AssociatedRichTextEditor is changed.

To reproduce:
- Associate the  ribbon with the RichtextEditor
- Subscribe to the DocumentContentChanged and start the application.
- The event is fired because the ribbon is making changes to the document.

Workaround:
void Form1_Shown(object sender, EventArgs e)
{
    ribbonBar1.AssociatedRichTextEditor = radRichTextEditor1;
}

RadRichTextEditor renders the text with a little bigger characters spacing than RadRichTextBox and MS Word.
Note: this text spacing problem can be observed in other Telerik controls as well.

To reproduce:
- Add RichTextEditorRuler and RichTextEditor to a form.
- Add some tab stops in the ruler and press the tab key.

Workaround:
void radRichTextEditor1_CommandExecuting(object sender, Telerik.WinForms.Documents.RichTextBoxCommands.CommandExecutingEventArgs e)
{
    if (e.Command is IncrementParagraphLeftIndentCommand)
    {
        e.Cancel = true;
        TabForwardCommand tabForward = new TabForwardCommand(this.radRichTextEditor1.RichTextBoxElement);
        tabForward.Execute();
    }
}

To reproduce:
- Add several RadRichTextEditors to a form.
- Change the icon of the FontPropertiesDialog.
- Close the form and force the garbage collector.

Workaround:
protected override void OnClosing(CancelEventArgs e)
{
    base.OnClosing(e);
    foreach (var item in this.Controls)
    {
        var rte = item as RadRichTextEditor;
        if (rte != null)
        {
            ((FontPropertiesDialog)rte.RichTextBoxElement.FontPropertiesDialog).Dispose();
        }
    }
}

To reproduce:
- Add some text so the scrollbars appear.
- Scroll up and down with the mouse wheel.
- When you scroll to the bottom you will notice that there is extra space after the document end.

Workaround: http://www.telerik.com/forums/backspace-key-does-not-properly-invalidate-editor#sP5qkJX4b0S8jwZ3MUGTmQ

To reproduce:
- Add RadRichtextEditor to a form and assosite it with RichTextEditorRibbonBar
- Start the application
- You will notice that the font is Agency FB.
- If you click in the editor the font will change.

Workaround:
void Form1_Shown(object sender, EventArgs e)
{
    radRichTextEditor1.Focus();
    ribbonBar1.GetType().GetMethod("HandleFontStylePropertiesOnCurrentEditingStyleChanged", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance).Invoke(ribbonBar1,null);
}

Workaround: load an empty docx document in the RadRichTextEditor and use it as a template
public RadDocument ImportDocx()
{
    RadDocument document = null;
    IDocumentFormatProvider provider = new DocxFormatProvider();
    OpenFileDialog openDialog = new OpenFileDialog();
    openDialog.Filter = "Documents|*.docx";
    openDialog.Multiselect = false;
    DialogResult dialogResult = openDialog.ShowDialog();
    if (dialogResult == System.Windows.Forms.DialogResult.OK)
    {
        using (Stream stream = openDialog.OpenFile())
        {
            document = provider.Import(stream);
        }
    }
    return document;
}

To reproduce:
- Add two tabs in a PageView
- Add RadRichTextEditor in the second tab
- Select some text to show the mini toolbar 
- Select the first page.

Workaround
void radPageView1_SelectedPageChanged(object sender, EventArgs e)
{
    if (radPageViewPage2.IsContentVisible == false)
    {
        radRichTextEditor1.RichTextBoxElement.SelectionMiniToolBar.Hide();
    }
}

How to reproduce:
public partial class Form1 : Form
{
    RadRichTextBox tb1;
    RadRichTextBox tb2;
    private bool shouldFocus = false;

    public Form1()
    {
        InitializeComponent();

        tb1 = new RadRichTextBox();
        this.Controls.Add(tb1);

        tb2 = new RadRichTextBox();
        tb2.Location = new Point(200, 0);
        this.Controls.Add(tb2);

        this.Load += Form1_Load;
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        StyleDefinition style = new StyleDefinition();
        tb1.IsReadOnly = true;
        tb1.Document.Insert("text 1", style);

        tb2.Document.Insert("text 2", style);
        tb2.IsReadOnly = true;
    }

    private void radButton1_Click(object sender, EventArgs e)
    {
        tb1.IsReadOnly = false;
        tb2.IsReadOnly = false;
        tb1.Focus();
    }
}

Workaround:
public partial class Form1 : Form
{
    RadRichTextBox tb1;
    RadRichTextBox tb2;
    private bool shouldFocus = false;

    public Form1()
    {
        InitializeComponent();

        tb1 = new RadRichTextBox();
        tb1.GotFocus += tb1_GotFocus;
        tb1.LostFocus += tb1_LostFocus;
        this.Controls.Add(tb1);

        tb2 = new RadRichTextBox();
        tb2.Location = new Point(200, 0);
        tb2.GotFocus += tb2_GotFocus;
        tb2.LostFocus += tb2_LostFocus;
        this.Controls.Add(tb2);

        this.Load += Form1_Load;
    }

    private void tb2_LostFocus(object sender, EventArgs e)
    {
        shouldFocus = false;
        tb2.IsReadOnly = true;
    }

    private void tb2_GotFocus(object sender, EventArgs e)
    {
        if (shouldFocus)
        {
            tb2.IsReadOnly = false;
        }
    }

    private void tb1_LostFocus(object sender, EventArgs e)
    {
        tb1.IsReadOnly = true;
    }

    private void tb1_GotFocus(object sender, EventArgs e)
    {
        if (shouldFocus)
        {
            tb1.IsReadOnly = false;
        }
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        StyleDefinition style = new StyleDefinition();
        tb1.IsReadOnly = true;
        tb1.Document.Insert("text 1", style);

        tb2.Document.Insert("text 2", style);
        tb2.IsReadOnly = true;
    }

    private void radButton1_Click(object sender, EventArgs e)
    {
        if (shouldFocus)
        {
            tb2.Focus();
        }
        else
        {
            shouldFocus = true;
            tb1.Focus();
        }
    }
}

When the RadRichTExtEditor.Document is rapidly changed not all memory is released

Workaround: 
Point loc = radRichTextEditor1.Location;
Size size = radRichTextEditor1.Size;
radRichTextEditor1.Dispose();
radRichTextEditor1 = new RadRichTextEditor();
radRichTextEditor1.Location = loc;
radRichTextEditor1.Size = size;

this.Controls.Add(radRichTextEditor1);

To reproduce:
- Add comment and try to select the text with the mouse.

Workaround: use keyboard to select the desired text

Workaround: explicitly set the font size of the spans in the heading paragraphs
foreach (Section section in this.radRichTextEditor1.Document.Sections)
{
    foreach (Block block in section.Blocks)
    {
        Paragraph p = block as Paragraph;
        if (p != null && p.StyleName == "Heading1")
        {
            foreach (var item in p.Inlines)
            {
                Span s = item as Span;
                if (s!= null)
                {
                    s.FontSize = p.FontSize;
                }
            }
        }
    }
}

The LocalizeStrings method of the FloatingBlockPropertiesDialog refers to the "Documents_FindReplaceDialog_ReplaceWith" string. This should be "Documents_FloatingBlockPropertiesDialog_TextWrapping"

Workaround:
public Form1()
{
    InitializeComponent();

    FieldInfo fi = this.radRichTextEditor1.RichTextBoxElement.FloatingBlockPropertiesDialog.GetType().GetField("radPageViewPage2", BindingFlags.NonPublic | BindingFlags.Instance);
    RadPageViewPage textWrappingPage = (RadPageViewPage)fi.GetValue(this.radRichTextEditor1.RichTextBoxElement.FloatingBlockPropertiesDialog);
    textWrappingPage.Text = "TextWrapping";
}

To reproduce:
Add image like this:
void button_Click1(object sender, EventArgs e)
{
    Section section = new Section();
    Paragraph paragraph = new Paragraph();
    ImageInline image;
    Telerik.WinControls.RichTextEditor.UI.Size size = new Telerik.WinControls.RichTextEditor.UI.Size(236, 50);
    using (MemoryStream ms = new MemoryStream())
    {
        System.Drawing.Image.FromFile(@"C:\img\delete.png").Save(ms, System.Drawing.Imaging.ImageFormat.Png);
        image = new ImageInline(ms, size, "png");
    }

    paragraph.Inlines.Add(image);
    section.Children.Add(paragraph);
    this.radRichTextEditor1.Document.Sections.Add(section);
}

Workaround:
Manually update the layout:
 this.radRichTextEditor1.UpdateEditorLayout();