Hey Splais,
I just sent an e-mail your way before I read this post. I used a Dave Brown engine mount for the .72 Saito- the mount is slightly longer than the included .40 size mount. I usually cut gaping holes for the engine so I don't really know. They have given you the original cutout for a .40-.46 size engine. The plastic cuts very easily, anyway. I use one servo at the present time. I used to use 2 servos for flaperons, but one servo got damaged in a crash so I went back to one servo. The plane can fly so slow, you really don't need the flaperons. 2 servos is good insurance, though.
Mounting 1 or 2 servos in the wing only takes a few minutes, so either way works well.