Hi Pingtang,
I'm not sure which scale you're working in, but for 1/72 aires, eduard and I believe verlinden all make detail sets for the Hellcat. Not sure about the engine question, the later engine (R2800-10w, with water/alcohol injection) should be correct for all Hellcats (-3s and-5s) subsequent to Bureau number 40633.
As for Hellcats at Midway, I don't think there were any. I believe the US navy started taking delivery of Hellcats in September of 1942, so there shouldn't have been any at Midway. Also, I 'm pretty sure that no -5s were delivered in the three color scheme. Someone may know better, but the photos of all the early -5s I've ever seen, even those that retained the rear windows were all painted in the single color scheme.
For the resin, I find that stuff noxious, I wear a mask when I'm sawing the stuff. You'll need a razor saw. It can also be really brittle so be careful not to snap it. You'll have to use superglue instead of plastic cement to attach parts. You'll have to test fit and reshape things and probably thin things down, especially if you're using resin cockpit sidewalls, other surgery maybe necessary depending on what you're installing.
Good luck with the model.