It has space for a standard PSU inside, but I’m pretty happy with this one:
https://www.amazon.com/dp/B0785GRMPG
I’ve been running it for about 4 years now.
If you have a fat GPU, you might have trouble with additional PCIe cards. You’ll definitely need more cooling as it only comes with one tiny fan.
This is patently false. Secure boot and hibernation are not mutually exclusive.