I would start out with what the manual says on low rates. If the Seagull Edge 540 is anything like my Skyshark it doesn't take much movement on the control surfaces to get a lot of action. I am running an 1800 mAH on board pack that I buy from one of out club members who sells them at $10.00 a pop. Just can't beat the price. You need no pumps, no 4-stroke fuel because they run great on any 2-stoke fuel that has at least 18% oil content and burn less fuel than a 2 stroke. There are a lot of people using 30% heli fuel but only if you are flying 3D. There is no need to use the expensive fuel if you don't have to. The Saito 100 or 125 is a very fine choice and if I were doing it all over again I'd go with the newer Saito 125. It uses the same block as the 100 with a little more hp. The 100 flys my plane just fine, its just I like a little more power when I can get it at basically the same size and weight. Enjoy your plane.