I think you have the others points covered, but the squeak from the osr could be the wheel nut. I have both my os nuts come undone not long after the service as the grub screws were loose, and had an initial squeak which became a graunch. By undone I mean 1/4 or 1/2 turn max.

Petrol small will be the breather or filler slightly loose and venting into the boot space.

These cars do like to be driven regularly.