According to AMD official website, the Ryzen 5000 processor supports only X470 (beta bios) and higher. It is AMD design and chipset limitation .
https://www.amd.com/en/chipsets/b550 For the USB disconnection issue, If there is Global C-state in the bios , please disable that option, it should resolve the USB issue.
As for the resiable bar, it is same idea that it is chipset limitation.
Yes, we have other motherboard section for X370 motherboards
Sincerely,
TY