Most turbo kits will retain the use of AC. Its some of the higher end manifolds/DP setups that wont allow for AC.

A turbo is more efficient than a blower, but in reference to what youre asking, depending on relevant modifications, PSI is PSI, so when youre talking about 6-8 or 6-10 or something along those lines, its about the same. Past 10PSI and I believe that M45 blower in the LS JRSC kit begins to lose its efficiency.

I would turbo a B18B....I like Rev Hard kits personally. Spray the IC black if youre worried about people seeing it.