1) There are something like four. AAISP, Cerberus and Hyperoptic IIRC. Perhaps Spectrum. Someone posted on Tuesday or Wednesday an Openreach link that showed the list, and also a link to the business ones with a few more.
Plusnet also have a trial running open to existing customers. If interested then don't try phoning. Register on the Community forums
and have a look around. There should be a few threads about how to get on it from outside like yourself.
2) There are a number of cabinet areas where end users can choose either. Only time will tell, but I don't see people being forced to move to an ISP providing FTTP from FTTC on one that doesn't. The place to check is this site
, which I expect currently shows VDSL2 and perhaps FTTPoD. (You can probably ignore FTTPoD, it costs thousands).
3) You imply you are with some other CP (Communications Provider) than BT for your phone. I don't think, (but am not sure), there is anything to stop you keeping your existing phone line supplier if you move to an FTTP broadband supplier for the broadband.
My broadband basic info/help site - www.robertos.me.uk.
Domains, site and mail hosting - Tsohost
Connection - AAISP Home::1 80/20. 200GB. Sync 75808/13984Kbps @ 600m. BQMs - IPv4