Multiple forums on one site

Hi. I’m VERY new to this and need help with 2 things. I will try to keep this brief. I have set up my wordpress pages and want to have 3 group discussion pages. Users/members must be able to post and reply and I would like if possible to have the posts listed individually somehow. What is the best (and easiest) way to achieve this? The other thing I would like to do is have users/members be able to submit pictures and videos to galleries (in the same group pages), allowing others to comment on them. Again, how is the best way to achieve this?