I don't think he's using fso, and afaik there's no way at all to have fs2 working with such model.
pcs doesn't crash. It seem crashed but

he's converting, and it requires helluva time to convert a complex model. Let it work in background for many minutes, expecially if your pc is slow. Give it up if it has converted nothing in 10 minutes, obviously;)
the best way to learn how to make a model for the game is to read tutorials (ipandrews, karajoma, etc etc). Most tutorials are for fs2 but FSO is an enhanced fs2, so if you can work for fs2, you can work for fso too. I'm not saying you have to spend months on the old fs2, just learn first what are the very basics of modding that game. You know, you can't just throw a brunch of polys into a converter and pretend to have a working ingame model;)