1: boost spike is when your boost goes over your desired amount for a half a second or so.
2: BOV flutter sounds like a horn, VERY distinct, and LOUD!
3: Some people do, others worry bout blowing a fuse, and over heating
4: Not to sure, i belive trent has one?
the gtech is only as accurate as the user. If you're not on a flat road, with a stiffly sprung car, and with a solidly mounted -- zero-ed out gtech, then no it won't be accurate
As for the smoke on start-up. If it is white, then this is normal for a cold car (condensation in exhaust, just the water vapor leaving). If it is light blue then it is most likely worn valve stem seals