tagging like facebook 'interests'?

i'm working on social networking site and currently trying to figure out a way to create something similar to facebook's "interests" section. (ex. i type in a comma separated list of my interests and they show up in my profile as links to a search query of ppl with that interest.)

it seems that "tagging" oneself with interests can automatically provide links to the taxonomy term corresponding to the interest, and there are lot of taxonomy modules to provide addt'l functionality...but i have a few questions:

-in your opinion should i use taxonomy/tagging for this or something like the node hierarchy.module?
-can you provide any insight into how i could possibly get the following accomplished:
--a) have the link result in a view that would search through multiple content types (forum topics, organic groups and other users) in that particular taxonomy term
--b) have multiple categories of tags - like [type of organization], [areas of focus], [location], etc. - and display them separately - right now, even though there are multiple fields in the profile, all tags display right-aligned at the bottom of the page.

i would appreciate any insights, as right now i'm just fumbling around trying to figure it out. thanks!