Regarding the potting: is it necessary to re-pot once the covers are fitted? Will it change the resulting sound/response a lot?
Do you mean is it necessary to re-pot because the existing pickups are already potted? Yeah, because there'll be air-space between the cover and the pickup - ideally you want it to be one "solid block".
Of course you could leave it unpotted, but it'll be more prone to squealing, whistling and feedback - OK if you're playing some mild blues, but probably not ideal for your br00talz project! :lol:
I don't think it'll change the sound much at all, except to round it off a little, no bad thing with RYs (IMO).