Petrol, don't expect more than 30mpg at most, insurance will vary wildly wherever you go, so try the usual sites like gocompare, add in directline, avivs (since those two aren't on the comparison sites) and take the best you can get to sky insurance and adrian flux. See if one or other of those can beat it.
Some altezza parts will be fine, some won't - bear in mind the engines are different depending on model, but the body parts should be the same in most cases.
As for comfort as a daily driver - I've driven nothing better in 14 years of car ownership...