That’s also true, but I have experienced an occasional issues when it would be stuck on downloading some package at 10 KiB/s because of bad mirror. Parallel downloads likely wouldn’t have helped in this case since it would select the same mirror. Obviously both issues need to be fixed though.
That’s the other way around. It’s an OpenGL driver that uses Vulkan under the hood. OP would need the opposite to have Vulkan on his card, but I don’t think it’s possible given that Vulkan is a lower-level API compared to OpenGL.