Hey Orkid,
Regarding the blow thru vs draw thru, that subject get tossed in the ring quite often in the turbo bike realms. It’s kinda like the oil threads. Simply put, they both work and if setup properly both work well.
I guess it comes down to what resources you have available. If you don’t have any welding or access to fabrication weather it be from yourself, a friend, or paid help then you’re setup is at the mercy of what you can purchase. If you do have access to fabrication, as you note you do, then your choices expand and the limiting factor comes down to budget.
I think blow thru gives you more flexibility for mounting and choosing your turbo, it can be mounted anywhere on the bike and can also make use of an intercooler. If you choose draw through you should choose a turbo that has a carbon ring on the compressor as noted by Blue and its best to keep the turbo in close proximity to the intake manifold for better fuel atomization; which might work great if you want the turbo mounted behind the motor.
All I know regarding cams (limited) is what has been noted above by buttcan and Blue, that being little overlap is desirable (the period of time both intake and exhaust valves are open at the same time). I believe this limits the pressurized intake charge from pushing the air/fuel right out into the exhaust. The cam that Sam pointed out does well in this area, with only a few degrees of overlap.
I have had luck using the stock carb rack on my setup. With a little prep the stock cable slide carbs seem to work well. CV carbs would probably work better if going blow thru, but if you are budget limited using your stock carb rack is an option.
A good resource for turbo bike knowledge and information is here:
http://forum.oldskoolsuzuki.info/cgi-bin/Yabb/YaBB.pl?board=forcedinduction
