Change website field in Leave a reply.

Yes I am a newbie and very fresh at this. I browsed forever for a theme and Brand New Day jumped out at me. Even your other themes are fun!
I would like to add a field (or remove/change website field) on the leave a reply/comments area. Basically, I would like a drop down category menu with a couple parent and a few children underneath. Then when folks place a post they can select a category, to which this can be stored in a right hand side bar area in respective identical menus/categories.
I also noticed if you place a post on home page it uses the title of the page and feeds the post into the recent comments widget in sidebar. I did not want this to happen. Just want an home page to be static and not affiliated with any posts. Is there anyway to do this? This is our site, should you need it to refer to.
http://www.youcanmakethisbetter.com
I am not sure if terminology I used is correct. Please forgive my naivety. I am very keen to learn. Any help would be appreciated. Thx