I say draw through becouse it should give a better idea of how much air is going in. but then it won't account for the blowoff valve.
the thing with the blow through is even though it gets all the air that goes on the motor that reading is saturated in heat and pressure and is therefore less accurate
if not there is no reason what so ever to run a blow thru MAF. they actually run better with a drawthrough MAF most of the time just because it doesn't have the swirl and agitated air going through it.
I have read that if you are not going over 10#s of boost, a BOV is not really necessary. I plan on keeping mine at 8# (at least initially), so I probably don't NEED one, but I think I would feel more comfortable with one.
that's what a bypass is for, it just routes the boost back. if you not running that then it will just try to backspin the turbo making a "toof..toof..toof" noise. but you probably already know that.
Go with the draw through MAF. Pressurized air that comes from the turbo will be alot hotter which in turn makes it less dense. The MAF will like the colder denser air better and will give you more fuel.