For what reason? Do you want to run LHD? To be honest it would make no difference at all unlike BMX where slipping out of a grind or not hitting it perfect will brake pretty much your whole drivetrain
This way you can get closer to destroying your rim everytime you spill something on it! If you don't already have a grind it might be a good idea to try as your braking power will increase, but to clean it use disc brake cleaner (or nail varnish remover) sprayed onto the rim and keep wiping it off and repeating until you feel that it is all clean. Then file your pads a bit.
Anywhere between 15-30psi will be fine depending on your style and what you ride. I have run about 8psi once but the tyre peeled away from the rim whenever I turned on the back wheel.
Really is a personal choice. I would go for echo flat bars and a longish stem (at least 115mm). Have a go on other peoples bike, see how high you like the front end and how much stretch you like.