I have an inf file for a user-mode driver for a device.
Does windows require me to get this driver signed? Are there any risks of not having this driver signed?
I know that kernel-mode drivers need to be signed.
The short answer is no; windows does not require signing for user-mode drivers on x86/x64.
There are no risks with not having it signed, and you don't have to pay the fee to have Microsoft sign the driver.
UPDATE: This is no longer the case as Soroush Falahati's answer will point out, please refer to his answer