For your first question, I assume yes, but I’ll let more knowledgeable users explain/link the how and why.
See USB Security / Security Warning On USB Input Devices.
Small note : don’t confuse an USB “controller” (a PCI device), an USB “port/plug” (the physical plug), and an USB “device” (mouse, keyboard, etc).
So, a single USB controller is responsible for several USB plugs and devices (even handling various protocols like USB2, USB3, thunderbolt, …).
Compare the different outputs of “lspci | grep -i USB” and “lsusb” (or “lsusb -vt”).
Or using the Qubes tools, “qvm-pci” and “qvm-usb”.
When you have 2 controllers like you, you can have several sys-usb qubes, each handling a separate controller.
This way you could use a sys-usb for “trusted devices” (your mouse, keyboard, maybe backup drive) using one controller, and another sys-usb using the other for “untrusted devices” (or more !).
On Qubes, you just have to be careful as AFAIK, the system-provided sys-usb handles your keyboard and mouse. It depends on your install choices.
Recommended docs :
But in vendor hardware documentation, I’ve never found which plug goes to which controller.
There are some explanations in the above docs, but it may be daunting for some users.
So, there is this thread : Figure out which port goes to which controller, but it’s kinda messy now (I posted there) ^^
Also, it may or may not depend on the internal wirings of your computer (but I may have misread the Intel docs about the laptop of the OP and be wrong on that).
It’s not that difficult, but depends on your computer knowledge -and- your security requirements.