The screws in the back are stabilizers for the wraparound bridge. They should help resist bridge rotation in the long term. At least that’s the theory.

am I correct in assuming those aren't really screws rather female threaded holders which the studs screw into?

those slots are huge and from my eye look oh so very slightly out of line...point being I would suggest using something more modern like an hex head...yeah, I bet you got totally anal and did your best to line them up (and perhaps they are "perfect" (a saying I'm fond of is "they took the last perfect tradesman and beat the cr@p out of him, put a crown of thorns on his head, then nailed him to a cross...point being perfection is a goal, not something actually achieved)), still to me something seems oh so slightly wrong. I rather hate slot heads as they bring out the real anal side of me trying to line them up...if they are only available as such then perhaps rotating them by 90 degrees (e.g.parallel to the neck) would blur things...traditionally I have found going that route makes things look more "correct" if for no other reason that 2 slots slightly out of parallel are less obvious than 2 sets of slots being out of line.

silver just brings it all out, perhaps go for black to mute their presence?

yeah, I know, nitpicking over what is some REALLY nice work.

Is that Brazilian I see?

Also, how do the pickups sound?
Any difference between those and say Seymours or something?