hippity_hoppity

At a cursory glance it appears to be using the CWT GPA platform. Rather low end, poor quality group regulated design which lacks safety features (OTP, UVP, OCP).
Should be avoided. There's probably better stuff available even if you're on a budget.
 
The Pure Power 10 is a much better unit! Choose that.
400w is plenty. A system with an RX 570 + Ryzen 2200G will need less than 250w.

My own rig would technically run fine off a 400 watt PSU (not very quietly but still) and it's got an overclocked i7 and Titan.

I mean, under realistic gaming conditions the 570 is going to use ~150W, under extreme unrealistic conditions (FurMark) the GPU will use ~195W.
I wouldn't expect an OC'd 2200G to use more than 95W considering it's a quadcore. Add RAM, motherboard, etc., ballpark guess under full stress is ~300W.
 
I used to run Ryzen 5 1600 + RX 580 with my 450W PSU.
 
You should consider undervolting the 570 (you shouldn't need to reduce clockspeed when doing this, unless you got unlucky with the silicone lottery).

Depends on how much of a voltage bump you need to go from 3.9 to 4GHz.
Personally, I would just try the highest frequency you can get with 1.35v.

Yes, it's enough.