1) Daily, there were 2-3 very active ones in my small town. Procomm Plus was what I used the most in DOS. This was also a stepping stone to IRC. It got to the point I was doing chores to pay for a second phone line for my bedroom.

2) The phone numbers were in a little ad box in the newspaper one time.

3) Most people seemed to bounce around to each BBS but there were communities within each that also seemed to stick there. I expect that was partially due to relationships that people had with the sysops.

4) It was a small East Texas town, so people were generally friendly. We were just kids, like 12 years old, having political discussions with adults. People would also trade or offer up gear they had. I remember inviting a high school guy over to my (parent's) house to install a 28.8k modem for FREE because he had upgraded to 56k. He just gave it to me for nothing. As far as I knew people just treated each other like people. I don't recall ever knowing I was being excluded from something because of my age. For a while there were monthly meetups at a local pizza place.

5) I wasn't interested in programming back then. I remember a lot of talk of hardware, mostly modems, one guy trying to convince every Amiga was the future, file sharing/warez (I downloaded Duke Nukem 3D from a BBS in 5MB zip files), chess and other games over FidoNet.