#1
so just i get a 5150 (120 watts) head and put it on to a cab with 150 watts and crank the volume will it blow? is it better to get a 300watt?
Setup

Ibanez SZ320
Randall RD75
EHX METAL MUFF
Mesa boogie single recto series 2
Line 6 Toneport
Mesa boogie single recto series 1
Digitech GNX4
#3
No, it'll be ok. I warn you that your hearin might not be. But that's your hearin, so do wat ya want with it.
#4
You'll be fine. Just make sure to match the ohms first.
AMP:
5150 combo
GSP1101 + Tech 21 PE60

GUITARS:
ESP LTD M-255 w/ SD Full Shred
Kramer Vanguard w/ JE-1000 active preamp
Douglas WF-150sn w/ GFS "Hot Lead" set

EFFECTS:
Bos SD-1 (boost)
AMT DT-2

My Youtube Vids http://youtube.com/user/mogar