1) What BSD are you using? -- NetBSD primarily, but I dabble with DragonFly.
2) Is that BSD your main OS? -- Not really. My "stable"/"desktop" NetBSD machine is quite capable, but doesn't do ALL the things I need. My daily driver is macOS "Catalina", that's my 'command center' and I SSH into other machines from there.
3) Do you use any other OS for any other reason? -- Linux for work (embedded/toolchain engineering for a company that makes speakers and headphones). Windows 10 for the cutting-edge games and video editing. I love my Atari ST, which runs good ol' fashioned TOS. Experimenting with FreeMiNT and Solaris.