A few quick questions regarding force carbing

Yes, around 10 psi to serve. Can't help you out otherwise, as I always simply carbonate at 10 psi, which takes about 1 week before it is really drinkable and 2 weeks before it is really right.

 

force carbing with high pressure is notoriously difficult to predict. but,
should be nearly carbed. might want to shake the keg to speed up the absorption of gas. you do risk over carbing the beer with 30 psi, so if you find you are getting close don't push your luck. drop the psi to 10 or 12.

who can tell? what's too soon? lower the regulator to 10, turn of the gas, vent a few times, turn on the gas and give it a try.

yeah. the regulator is supplying 30 psi to the headspace at all times (that's why is called a regulator). if you lower the pressure but don't vent it, expect a the beer to pour from the faucet like a rock

you can make life easy and not rush things. just apply 10 to 12 psi, wait a week or so and enjoy. or do it a bit more conservatively. i will blast 30 or 40 psi immediately after kegging and rock the keg a few times. let it sit cold for a few hours. then back the pressure to 12, without venting. in a few days it will be fine. the initial high pressure blast just gets you there a bit quicker without the danger of over gassing.

btw, if you want to dial in your vols precisely, you really can't mess with high pressure force carbing too much. too many variables.

Cheers.