pretty sure ka-e tranny wotn work with sr.

anyways, about the aftermarket support, what do you mean?
the ka24DE and ka24E share the same block,

rods, pistons, rings, same.
all it is just that if you put in certain pistons, your compression ratio would be 1 point lower or something.. i forget.

go to KA-T.ORG and search, you'll come up with good results.

KA-E is good enough for pushing upto ~300rwhp.
the E doesnt have oilsquirters like the DE, so you couldnt take the power level as high as the DE.

gl if you plan on turbocharging it.
noone here has much good info about the KA series, well, at least i dont see of any them