Chain tool?
Is that a cassette lock ring tool top right? I would recommend one with a centre pin if you don't have one. Just that little bit better. If you already have one, not worth buying another.
Got chain tools on my multitools, but they can be hard to use, so that's probably worth investing in a decent one.
Yes, that's a cassette lockring thingy.
Yes, I think I'll get one of those if/when I need to change the BB.
spoke key, Crankset tool, cone wrench
Good one on the spoke key, although I haven't needed one thus far.
Top row third from the right is a crankset tool (if you mean the thing that pulls the crank off the BB)
What is a cone wrench and what is it for?
at least one multitool !

ring spanners for brake cables / muguards / brake mechanisms / seat posts etc
Have a multitool on each bike (otherwise I'd forget it) so I don't need one in the garage too.
I do also have combi spanners, on my "general purpose" tool rack further along the wall.