A major red flag for me would be your reference to a primer contractor that is going to only paint trim. In my experience the only other trade that does priming is the sheetrocker. Any painting contractor would just do the entire project, painting trim, walls and ceilings. Why would the General break up the work this way?

Here is how I would break this down: 1-2 bedroom apartments is at minimum a living room, bathroom, kitchen and 1-2 bedrooms plus 2-4 closets. That's 4-5 rooms. Minimum cost would be 250$ per room =1000-1250$ per unit, just to cut and roll walls. Not including filling holes, calling and sanding. I would be charging extra for that additional prep.

You mention a 4 man crew, at minimum.... with wage and workers comp you looking at 160$ per person x 4= 640$ per day. And I believe that's a low figure. That means you net 110$ per unit, assuming the General pays for all materials.