1) Fly with the cowl on but make sure you have good airflow over the cylinders. Also, leaving the cowl on doesn't mess up your CG.
2) About 10% ethanol, it varies by state, is in gas. From what I read, most gas engines now days have diaphrams in the pump made of rubber that resists ethanol.
3) I use 87 octane, 10% ethanol gas mixture and a 8oz of Lawn Boy oil at 32:1 for two gallons for break-in. I will switch to a generic two stroke weed eater oil I got from Ace, should be ok. Reason you want to use two stroke oil is because it has additives that help the engine. Outboard boat motor oil doesn't have those additives (that air cooled two strokes need) because boat engines don't need them as they run steady rpm and temperature.

Also, during break-in, the engine parts are going to be wearing in, ie. mating. That will create extra heat. You need non-synthetic oil so those parts can mate in properly. Synth. oil is too slippery and parts will take forever to mate. You need to run either more oil rich mixture or richer fuel mixture so that the oil can take away the extra heat in the engine during break-in process. After break-in (I think 5 gal. of gas) you can use synthetic oil. Some can be mixed at 50:1 or 100:1. Periodically check your spark plug because that's the best way to tell whether you're running the engine too rich in oil or not enough oil thus heating it up. If engine has too much oil the spark plug will be black and wet. The spark plug will be white if engine is running too hot and not receiving much oil. Oil removes heat and not having it makes engine run hotter. You could theoretically have a rich oil/gas mixture yet run the engine too lean causing lots of heat. Basically the result is that not enough oil is getting into the engine because either the needles are too lean or there is not enough oil in the gas. Just because you run synthetic oil doesn't mean your engine runs cool. Remember that oil absorbs heat and it takes it away thru exhaust. It's not about reducing friction between metal parts but about having a medium such as oil that absorbs heat and removes it from the engine. It's the same reason why heli pilots switched to 30% nitro. The gallon of that stuff has higher oil content that removed lots of extra heat from the heli engine thus helping it run cooler because all that nitro made for a hotter combustion. But that high nitro content help create more power in the engine. It was because of the extra oil in the fuel that made running 30% nitro possible, otherwise the engine would melt. Same with gas engines. You need oil that removes heat from the engine, plus you need oil for lubrication. Personally, I'm going to be removing oil from my gas and observe the spark plug to see if I'm running too hot. Right now at 32:1, the spark plug is way too black and wet. Next is 40:1 mixture, but after break-in and tweaking the needles.