6 lugs 20'' or 22'' wheels

[c3888]

Newbie here.
Trying to understand the wheel specs on a 1970 with disk on front. I am a bit lazy, I have not taken off the wheels yet. I know I have to do it, and will when the time is there.
But, as I understand it:
The wheels are lug centric (not hub centric) - correct?

What is the dimentions of the hub (center bore)?

Can I use bigger center bores without any issues?

How wide can I do? 8-9-10? it is different in front and back?

Backspacing - this I must measure for sure - but what will typicaly fit on a 70 stepper?

Offset - this is also a measurement job - but what do you folks run on?

Should I stay with the 6 lugs or convert to 5? There is a lot more to choose from on the 5 lugs, is it not?