It actually has a 90W internal power supply. With 20+4 pins ATX, 4+4 pin CPU/EPS, 2x SATA and 1x Molex connectors. Power board inside the case and AC-DC brick. I got my case yesterday, I can show you photos if you want...
It wasn't easy! The shroud on that thing makes it hard to even fit it on the bracket. Then if you add an optical drive like I did it becomes even more difficult to insert the assembly into the case. But the card is badass, handles 1440p well enough that I'm not considering getting a Vega 64 at current prices lol.
If you opt for an SFX-L PSU you have about an inch of clearance for the cables, it can be really difficult to connect them and there's definitely not enough space to add a 2.5" drive there. The 120mm fan on that power supply is really quiet, but the build overall isn't so if I had to start over I'd get the Corsair SF600.
All your assumptions are correct! More air to the GPU is what works the best, for that reason I also keep the case vertical. Otherwise it gets pretty hot in there.
Newegg links are up now for the Ryzen 3 2200G and Ryzen 5 2400G:
Okay, but why? Xeon CPUs are on here, and they fill pretty much the same niche.