#1
is the david gilmour's black strat some kind of custom made guitar?

can i buy a "all blac" strat like him?
#2
No, but it's pretty easy to make a replica.

Take a black strat, black pick guard, and a vintage stained maple neck.
Winner of the 2011 Virginia Guitar Festival

Protools HD
Lynx Aurora 16/HD192
Mojave, Sennheiser, AKG, EV etc mics
Focusrite ISA828 pres
Waves Mercury
Random Rack Gear

65 Deluxe Reverb
PRS CE 22
American Standard Strat
Taylor 712
#3
Yup, as above.

David Gilmour changed his pickups a few times, it also used to have a white scratchplate. He also has a switch to get the neck and bridge pickups, if you're interested.
Call me Callum

Current gear - 06 MIM Strat, '02 Epiphone Les Paul, Peavey Rockingham, Tanglewood TF8, BLACKSTAR★ HT-5 Combo, EHX Holy Grail, Boss DS-1, Arion SFL-1

Newcastle (and Port Vale)
#4
Adding on to the above again haha.

His red strat has some EMG pups, and the set of pups in his current strat are true single coils made by seymour duncan. What the hell, look it up. http://www.gilmourish.com/?page_id=66

"In November of 2006, Fender announced that they will be issuing a replica of Gilmour's modified black Stratocaster."-wiki/gilmour I'll be damned
Winner of the 2011 Virginia Guitar Festival

Protools HD
Lynx Aurora 16/HD192
Mojave, Sennheiser, AKG, EV etc mics
Focusrite ISA828 pres
Waves Mercury
Random Rack Gear

65 Deluxe Reverb
PRS CE 22
American Standard Strat
Taylor 712