Dunno about "foreign" circuits .... my local on eis Cadwell where the paddock has only recently been tarmacked. No garages and no power outlets.
Brilliant circuit though, I consider myself very lucky to be so close.
On gennies ... go for at least 2kW because you don;t want to run near 100% capacity all day. Honda engined are the better ones. I borrow an old battered Honda engined genny from a neighbour, and it starts easy and goes all day. It's well battered and abused as it gets used on a building site the rest of the time.