Sergey, you seem to have answered me while I was writing a follow up:
"Problem is, perhaps, that the selected text is protected using styles. I've turned off the rvpaoStyleProtect, and I've tried to set the selected text to another style (where among rvpaoReadOnly and rvprModifyProtect and rvprDeleteProtect are turned off) using code. Unfortunately, I'm unable to set the desired styels using ApplyParaStyle(); and ApplyTextStyle();. It just won't change.
What's more, I find that the CurTextStyleNo property does not hold the correct information... Obviously, I'm experiencing some newbie problems, as such a sever bug would certainly be rectified by now."
To answer your answer, I've checked rveEditor.ReadOnly = False. I'll continue to investigate my protected/unable to change styles problem, but please come through if you have any input. Thanks in advance!