Welcome
1. I'm 6"2 but only had coupe's. I used to fit in the 350 just fine, and current fit fine in the 370. But not had Roadsters. Will370z has roadsters and is even taller than me, so must be fine
2. Personal preference really. I'm not a fan of the roadsters, but many are.
3. I find them fine day to day, as long as they are not silly low with big bodykits. Returns reasonable mpg considering displacement. Boot is surprisingly spacious too.
4. You should be able to get a GT standard DE model for that price, maybe even with some nice mods if you are lucky
Happy Hunting