Need help with user generated content

I am attempting to create a site which would be mostly user contributed similar to a wiki. I have an idea what I need to do, but Im not sure how much I can do with current wordpress plugins/ features compared to what I’ll have to design from scratch. I could use some guidance in this area.

Here is a general rundown of the site.

1. I have a long list of categories that users can submit information to.
2. Suggest Topic:
i) Input topic Name (Required)
(1) Check for existing topic (also checks blocked hobbies list- adult oriented, or illegal activities)
(a) Checks if blocked
(i) Select * FROM block_cat WHERE name =_________
1.
(ii) Yes- Display “This topic is not permitted on this site”
(iii) No- Proceed to next step

(b) If exist- Display matching topic
(i) Is this your Topic?
1. Yes (display’s link to matching topic)
2. No (continue form)
(c) If doesn’t exist- proceed to next step

ii) Select Main Category from list (can have sub categories) (required)
(1) If secondary category applies (Default: No)
(a) Select secondary category from list
iii) Submit
(1) Submit will create a blank post that will list under Category heading (Pending status)
(2) Link will be marked with a symbol to indicate empty page

3. From list of topics, users can select post that have not yet been filled out and enter relevant information for each post.
– I think I would have to create a custom database table for this
– Blank fields will display a link to enter information.
-clicking the link will provide a pop up box to enter the requested information and submit to database.
-Text fields will need reviewed if user status is less than “trusted” -Selection boxes will be auto accepted.

— There are some additional functions that I’ll implement, but that is the basics.

So the question is, when I create the functions to reference the database (custom or existing), where do I include them?

And the custom forms, should I just make my own page template that will insert the data in the appropriate table?

I am going to be using a buddypress theme. I am hoping this will have some of the functionality I need for user registration and all.