If she's driving a Fiero - she's used to a ride that is not Cadillac quality. The VX is firm - those who like sports cars like the ride. You feel every twig or line in the road - I like that, Cadillac drivers do not. My assumption is that being a Fiero driver - she will.
General maintenance parts are pretty much off-the-shelf for other Isuzu/Honda products, and since there were so many made, the maintenance parts are easy to come by. At some point, the VX specific parts (body, etc) are going to get tough to find; but suprisingly enough, they have not becaome that way yet. There are usually a few in the scrap yards that can yield the parts you need as well.
Tires - I'm running 285/55/18 Pirelli Scorpions right now - that is wider than is suggested for our rims, and I did have some problems with proper seating of the tires, but a qualified, up to date tire shop should be able to fix you up. Looks like you are considering a 2001, and the 285/55's are very close to stock diameter - eliminating all the issues with speedo correction, etc. Oooops - just noticed it's a '99 - don't know about tire sizes for those - but if it were mine, I'd go with larger diameter wheels with lower aspect tires - I just think the VX looks better with "more wheel". Good luck - and welcome to the family!!
"If you're not living on the edge --- you're taking up too much space!!"