C&C Is this appropriate?

Depends on how you use it. One of the advantages of grids is that they can be assembled any way you want, while these panels are connected. They are tall enough, and the spacing of the bars is small enough, to work, though. If you needed to have a door, that might be a problem, but otherwise it looks fine.

Those are fine. The ones I've seen aren't quite as sturdy as the other grids, so you may need to reinforce it, especially if you plan to do a loft or have other animals/kids that might bump into it.

Yea, that's the thing. You can't really customise it which is a shame. I'll keep looking for cubes. Also does anyone know of pet barn stocks hay?