The buses can be a little hard to find, I've only transited to T1/Concourse D, not to T2, but as far as I know it's the same buses. However for FZ there are usually dedicated signs with FZ branding (not the case for D gates, just regular blue signs saying D gates, FZ has additional signs). I've taken it from Concourse B transit security, basically you need to go backwards through security, or if arriving stay pre-security, it can be a little hard to find, so just ask someone. Buses kind of go ad-hoc when they're full enough or have waited long enough, I'd say about a 20 minute interval, give or take 5 minutes. The drive can take up to 30 minutes and stops at T1/D gates along the way.

No boarding pass check at all I think, I didn't have a boarding pass and only checked in at the transfer counter at the D gates, so got there without a BP, might've showed my e-ticket but don't remember now.