what size are the minifan pro's? my memory sucks, so you are gonna have to refresh me..............is this for 70mm application, or smaller? if it's 70mm, I would look into the WM400MKII from Velocity RC. if they don't have any in stock, you can check with Gary at Efflux RC as he carries them in stock. if it's 60mm, you can look into the WM300 fans. for the money, you can't beat any of the WM series IMHO. 5S should be more than enough for your needs. in fact, 5S might be too much, but you'll have to check into that. I believe on 5S, the WM400 is putting out about 6+ lbs, for a pair of them. that should push this baby around the sky very well. plus the efflux is fairly high and you don't have to worry about an exhaust cone.............it's already done for you. you just have to make a straight pipe from the fan to the exhaust. the other good thing about the WM fans, is that the motor is up front, thereby making it easier to CG, especially on a plane of this design. something to consider at least.
that sounds like a great way to apply the resin, especially on a foamie. I've never tried it that way, so I'll have to give it a whirl some time.
you can thin the eposy with denatured alcohol and stipple it in with a brush. it will increase your work time and stretch the resin over a larger area. I've done it this way before and had some good success doing it that way. with balsa, I'm guessing that if it's too thin and sprayed through a bottle, the resin soak would be huge and add a lot of weight to the frame. would be worth experimenting with though.