You can use option called "Watch" every thread which u want to follow and then will receive notification's if there is something new there.
"Can ask for weird stuff" doesn't sounds good/safe tho. There is a certain rules that in Request's category have and that's how we can prevent being a total mess tho. U can ask for everything as long if it's fit on our forum rules tho.
I think it will be fit on Celeb tho. Another option it's Other category.
If u want to search something from specific category u can use Advanced option where u can have a couple of more option to choose.
Could be, but "reddit style" and forums based on XenForo are do not have unlimited stuff or if it's possible will take so much effort, time and etc. to make it possible.
Like POKI said...