#1
if i was to import a cab.. and use it with a head from the same country it should work yes? IE ---> power ---> stepdown transformer ---> cab+head it will be fine with an imported head and cab? what happens if i use a cab from where i am with an imported head?
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
#2
Unless you have some weird plug cab, a cab, which is unpowered, is universal (provide you have proper ohm and output wattage). The HEAD, on the opther hand, is not.
Ibanez SA-120 (ed.2006)
BluesJr 1996-B + cathode follower + texas Heat
Crate CPB150
Homemade 4 x 10 cab Bass closeback
Metal Muff
#3
The power system that the head is running on has nothing to do with the cab.

Just make sure that the Ohm load from the head matches the Ohm load of the cab.
#4
Yea speakers are pretty much speakers. Ive never seen euro, asian, american etc speakers before. As it doesnt use any kind wall power they will work anywhere.