1) Is there a way to configure the script so that if you want to FIX a thread to the top, it will only show up at the top for the forum where it belongs and not show up in the ALL CATEGORIES forum ?

"All categories" displays just all threads of all categories and thus of course all sticky threads, too. With a code modification this would be theoretical possible, but it wouldn't be that logical. Do you need something like a category overview?

2) Can we install TWO seperate "my little forum" on the same domain? Basically will it create a conflict if I have TWO seperate forums on the same domain?

Yes, that's possible. Just specify different "session prefixes" ("session_prefix" in the advanced settings) for each installation to avoid authentication conflicts.

3) Can we disable the private email feature so that forum members cannot secretly email each other?

This is just normal e-mail communication. If there wouldn't be a form field for the email address the users could also post their addresses into the message body.

4) I am presently using DCforum+, it's a mySQL php based forum. It would be nice if I can import all the existing threads and posts into MyLittleForum so that I can maintain the continuity of discussions.....

I don't know DCforum+ but if it uses MySQL it should theoretical be possible.

Alex