Comfort is down to what ever seats have been fitted, scimmies are reknown for the front seats falling apart. Fuel consumption is poor, mine has an auto box and returns about 20 - 25 mpg, worse if your spanking it down the M11. But its great fun upsetting the BMW drivers who wonder WTF has just gone past them.
Spares are not to much of a problem, many new parts from specialist dealers. Other parts from the Bay. Get the CD rom manual which lists in at the end where a lot of the parts were used elsewhere. i.e. door handles from Mini Cooper, rear hatch from Lotus, front suspension from TR3 etc.