1) Several times a day, generally Telix. My parents had to get me my own line so I would stop clogging up theirs! Especially once I found chat systems.

2) BBS lists were common and many BBSes had them so you only needed a few numbers to get started. Computer stores usually had them too.

3) A city would have dozens or even hundreds of BBSes in larger markets. Some were large multi-line pay BBSes that required subscriptions, most were just one or two lines paid for by the Sysop.

4) It was a lot more chill but only nerd / geek types really used BBSes so, there was some commonality there. More of a sense of overall community.

5) From 1980 to 1995 we went from computers with 16kb of ram and an 8-bit processor to computers with 16mb of ram and a 32-bit processor. There was always some new tech to talk about. It was a very exciting time!