Sense1,
I believe it is 10 in total, to be manned by RAF Aircrew, given the US's attrition rate and an expectation that ours will approximate it, 3 would just not last that long so the prudent man got some extras. As for the funding, I believe MM may well be able to give some idea as to where the MOD is saving a load in the ISTAR world.
ALWAYS assume NEVER check