BuddyPress.org

If you’re using /installed WP 3.0 that now combines single site and mutli site (blogs) in the one package however you do have to perform some manual file adjustments to enable multisite functionality in the backend from where you then follow the instructions to complete installation.

You can follow this guide to setting up multi sites:
https://codex.wordpress.org/Create_A_Network

As for BP forums have you enabled them in the backend? if you look in the dashboard at the BP section menu links you will see a link to ‘Forums Setup’.

Profiles is perhaps more a question of personal taste? I personally wouldn’t say that the profile of the default theme is particularly unintuitive, but that isn’t to say there isn’t room for improvement; obviously one can re-configure it somewhat if one uses a child theme and copies the files over to work on; also thre are a few newish plugins to add things like ‘User Stats’ and or ‘Follwers/Follwing’