Everything wrong with our cheap Cadillac BLS 2.8 V6 turbo. Can we fix it?

We bought one of just 12 road legal Cadillac BLS 2.8 turbos from a total of 40 sold in the UK. Under the skin it's a Saab 9-3 Aero but there's a few differences.
Having been parked up and not used much for a few years, obviously we were going to encounter teething problems. Wires, pipes, sensors, fluids, fault codes... the usual. But can we fix them?