budget seems fine, should get something around the 05 to 06 reg for that, condition is everything on the zed, if its tatty walk away. or haggle them down alot.
long drives are fine engine at 70 mph sits at around 2.5k to 3k rpm
i found the seat gave me hip ache but im funny; most find the zed very comfortable.
insurance try admiral; adrian flux, i would say chris knotts as well but they wont touch you till you've had a performance car for more than 12 months and not crash it.
sat nav is crap i'd find an after market one.