No comment on the drum kit thing. Important principle, though; you should NOT peg people's share of gig money to how much their personal gear is worth. If someone doesn't have good enough gear to gig with, they should make an investment or find another band, and as long as their gear passes muster, the band should let them spend as much or as little as they want. Otherwise you get spending wars and endless squabbling over I-just-bought-a-new-pedal-so-i-should-get-more-money, or resentment because "Billy has rich parents so now he gets extra gig money too?"
In theory, it would make sense for the PA to be the singer's contribution to the band gear supply. They're not spending on amps and guitars and drums, and it's mainly their "instrument" - their voice - that the PA amplifies. In practice, it seems like that's never the case. They seem to feel that they don't need to invest in gear because their voice is already part of their body. And the thing is that because the success or lack thereof of the band will largely rise or fall with the singer, a good front person is worth an equal share even if they don't contribute any investment in gear. My preference is that one band member owns the PA, and whoever it is gets an extra share or half-share to cover it.
The other way to do it is to break out a list of band jobs; then everyone either shares them out equally, or you assign a "share" to each of them and gig money gets split according to who's doing how much. For instance:
Practicing and performing - everybody does this, of course, so 1 share.
Provide rehearsal space
Make the bookings
produce marketing materials/maintain a website (beyond a facebook page)
Provide a PA
And whatever else you can think of. In my current band, the guitarist has the practice space, he and the drummer each provide PA components, I do marketing and website and the singer does bookings. The guitarist also did most of the work on producing demos. He really should get the higher share of gig money, but doesn't care about it. So since everyone's contributing something beyond practice and performance, we make it even splits.