Pressure depends on how much of a hurry you are in, you can carb up at your serving pressure, it will just take a few more 'connect, remove, shake' cycles, to get a good level of carb; or you can bump up the pressure and get the gas dissolved a bit quicker. One tip is to not fill the bottle too full, then you can get more volume of gas in per 'connect' ( still squeeze out any air first... ).
I use the caps as above, usually fill a pet bottle first from the fermenter, then the keg(s), then the rest into pet bottles. The bottles then go into the fridge for a day or two to settle ( the first bottle usually has a bit of sediment in it too, even after dumping the first 50ml from the fermenter tap, so I get the clearest beer into the kegs, midstream if you like, ha ha ). I then decant the bottles into another bottle to leave the sediment behind, and gas up from there.
You can get an early taste of the beer without rushing the keg carbing and know what you have to look forward to. I have found that the taste is stronger than the keg beer (esp. the hops bitterness ), I think some of the flavours are heavier/ denser so sit in the bottom of the fermenter, or possibly they are released from the yeast & trub when going into the bottle. Haven't noticed any oxidation issues from the decanting but mostly its consumed pretty soon after carbing and kept cold, so longer term you may notice it.
If you have the plastic type carb caps, search for ' easy (poor mans) cpbf ' for a good way to fill pet bottles from a keg for longer term use. ( I have nfi how to post links... )
Here endeth the essay lol, hope you can get some useful info out of it.
Cheers.
