How long is a piece of string

First job, get underneath and check for rust (boot floor, inner and outer sills, inner wings etc) and get anything crusty rectified.

Lowering is fairy straight forward - I'd buy a full set of springs and shocks and I'd replace all the bushes at the same time as they are probably past it now! Full geo will see it handling like a go-cart!

Wheels, you're limited by the size of the arches. Anything over 15" in diameter looks a bit soft and anything over 6.5" wide will need arch extensions!

Looks - depends what you want, you could keep it OEM with some XR2 parts or go balls out with an aftermarket bodykit!

Not sure whats available exhaust wise for the 1.1 but anything XR2 could be modified to fit the 1.1 downpipe I'm sure.