RE: TRAINER FUEL & glow plugs
Two or three spare plugs are all you need. If you blow 2 plugs in a row it is often a sign of a faulty engine possibly a peeling liner.
Get fuel with 2% to 3% castor oil and the balance synthetic oil if you can. !0% nitro will do fine 15% OK any more is too much.
Tell the model shop owner the engine you have and he should keep you right.