The power cables are plenty capable of handling the current required.

Batteries, a 7 cell 8.4 Volt NiMh pack, about 700-800 m/ah. They're good enough for about 8 minute flights a pack.

DON'T go above 8.4 Volts, the electric motors can't handle anything more. They will burn out really quick (like in a couple of flights) if you go to 8 cell 9.6 Volt packs.

The GWS supplied motors aren't long life anyway. THe EDF 50 3 blade units seem to last about 30 flights. Can't say what the new EDF 55 6 blade units will do, but probably about the same.

Retracts? No way. They will add weight. Just delete the undercarriage and the nose wheel steering servo, hand launch it and land it on is belly.

The secret behind this model is keeping the weight DOWN. It's borderline in the power department anyway, though if kept on the light side, it will fly o.k. (but not quick.)

Once the original motors have died, then look into some small brushless motors as replacements.

There have been plenty of threads on this conversion on this forum and I am sure that those who have already done this type of conversion will gladly share their experiences with you.

Good luck