RE: Prop Lock Nut
I took the same route as you when I first started with four strokes i.e. using spinner nuts and I had a similar experience. I use Truturn spinners with double jam lock nuts exclusively with all my Saitos primarily for safety reason (they don't loosen easily in the event of a backfire). Using an electric starter makes starting a breeze and safer too. Turn the prop cw until it hits compression, then apply the starter. In this way, especially for larger engines, the momentum will be sufficient to rotate the engine through the compression stroke. Also, tune your engine well with a tachometer, and don't flood the engine before you start, as these may cause a backfire. Hope this helps