From what I've gathered nv3500s are notchy and clunky compared to about any other manual out there as far as smoothness goes. I park on an incline and for my reverse to engage without fighting I have to shift to 5th or any other gear before it will align the reverse gear. As far as your grinding mine doesn't grind except the first few times when I wasn't used to it going from 1st to 2nd gear, it would grind if I applied too much pressure left so it kind of has its own personality if it makes sense. Now I've learned to shift it without a problem. How long have you driven it for. When you say it resists you at lights do you mean it takes you some effort to find the 1st gear gate for example?
And as far as your grind into gear does it only happen in reverse or does it do it in 1st taking off too?

 

ive driven manual my whole life just not a Chevy. I’m used to small 4 bangers. So I put the clutch all the way in and go to first and it’s almost like the clutch isn’t fully engaging and there’s something keeping it from going into gear. It’s strange and it only happens occasionally. I discovered what you’re talking about though, putting it in fifth to align reverse and since I started doing that I’ve never had an issue with reverse. Just occasionally first throws a fit and doesn’t want to engage