P-39 Airacobra from ebay

Hello,

I bought a second hand Cox P-39 Airacobra off ebay. It has some fuel residue on it and the engine is sticky and won't move. It doesn't come with any instructions and I am a little unsure of how to attach the fuel line. I have made a video to show the model:
https://www.youtube.com/watch?v=pMhyAKxPNHY
There are two sets of holes in between the canopy and the engine. One set on top saying "Full" and "Half full" and one on the bottom, which doesn't say anything.
Does anyone know how they work?
What could I use to clean the engine and plastic?
Any advice would be really appreciated.
Thanks
Simon

Looks like you got it figured out, the hole (s) on bottom are either for routing fuel line, oil drain, or screw access. I'd use windex (window cleaner) and an old toothbrush to clean.