1) I was hooked on day one. Logged on every day, mostly read message boards, paged/chatted with sysops or played door games at first. But very quickly fell down the "hpcva" rabbit hole, which paved the way for the infosec undertones of my career. I'm fuzzy on the program names, seem to remember Telex, Terminate, ToneLoc (a random dialer where you'd scan an entire NPA for interesting carriers).

2) We got a small list of boards from the family friend who helped install our modem, and after you had the first few boards most of the logout screens had a long list of others. There were also lists (by area code) that you could sometimes download from the files section, or some of the grey area ones were traded (usually required NUP/NUV anyway -- new user password/new user voting).

3) Both. Some 20+ node boards were legendary. Some boards were so empty that the sysop would break in after barely giving you time to login because they were so happy to finally see a caller.

4) Drama seemed to matter a lot more. Today it's mostly just drive-by arguing on X or something, and after you exchange unplesantries you move on with your life. On early boards (and into IRC) the communities felt more insular and drama really could divide an entire community and leave lasting marks. Topics were all over the place. Flirting seemed more open, and plenty of fights were just over girls because at the time the female side of tech was extremely unrepresented.

5) How to troubleshoot/fix computers was common. Discussing specific programming languages really bloomed with Usenet and IRC. The t-files on boards that were most interesting to me were about making computers do things they weren't meant to do. Fravia/ORC+ reversing tutorials, or phrack, etc etc.