The TT46 is an easy to use engine, will run happily on an OS No. 8 with 15% nitro. Props for the trainer would be an 11x6, I would not bother with the 11x7 as there is no need for so much speed on your trainer. The 10x6 is for speed (about 13.5K RPM) and enjoy that on some fast plane. You can run on 5% nitro also for a trainer and does not really matter if you go 100% synthetic (Cool Power), semi synthetic (Omega) or full castor. I use Cool Power 15% heli fuel, works great as I hate castor on my planes.

Breaking in is always an issue (different people will say different things), what a lot of flyers here will normally do is to run her a little rich (about 3.5 turns out) at say about 50% throttle for about 2 tanks, tune her and then just fly. When you fly her let it be on the rich side, maybe say 500-600 RPM off the peak. Take it easy for the next few tanks. This engine might not be fussy but it does not like to be abused, don't run her too lean, once it heats up a little too much it will lose power.

My TT46 starts with a back flip and is totally reliable, great value for money.