@tutafourabit : Welcome to the Win-RAID Forum!
Since Win7 doesn’t have any NVMe driver in-the-box, you have to integrate the related MS NVMe Hotfixes (see post #2) into the boot.wim and install.wim of the Win7 ISO file. Once the OS is installed and running fine, you can switch to another NVMe driver. Its choice depends on the NVMe SSD manufacturer.
The USB problem is caused by the fact, that there are no Intel USB 3.0/3.1 drivers, which do support Windows 7 and the newest Intel USB 3.0/3.1 Controllers simultaneously. Nevertheless you will find a solution within >this< thread.
Good luck!
Dieter (alias Fernando)