If you are telling about limiting the search to a user and certain boards, you can do this by going to https://bitcointalk.org/index.php?action=search;advanced.
First suggestion is a good feature and IIRC it is already suggested. I support it. I don't know whether there is a need for second suggestion but it would be handy.
Searching by topic for own created threads meant for the idea as it makes it a lot simpler to find topics created and not having to scan though all your pages of own comments and skim though pages of comments. Having find topics created self makes lot simpler and easy to locate.