Yes, 3.5" fit in. Adapters are included for the 2.5" hard drives. Perhaps it is important to know that there are no problems with new, unformatted hard disks, but I assumed that I could simply plug in my existing external hard disks and they would be read. Didn't work that way. I had to reformat all of them and copy the contents again. Otherwise, the box does everything as expected. I can recommend it.

The unit fully meets the desired requirements.

I have no problems. I have measured my plates. But normal 3 1/2 inch are no problems. As described above, it has an adapter for 2 1/2 inch plates. I guess that's the height you mean. But with 3 1/2 inch you take the plates out and the plates fit. As I said, you take out the adapters for 3 1/2 inch plates. I don't know of any plates that don't go in there. Fits securely. No problems.

Hard disks that are higher than 12.7 mm will not fit.