A1: To see the HID devices, add
usb.generic.allowHID = "TRUE"
for details, refer to USB HID in:
A2: One keyboard is enough I think, because you won't use two keyboard at the same time, right? The issue is how to avoid the duplicate shortcuts between host and guest, right? So, try go to VMware Fusion -> Preferences...-> Keyboard & Mouse -> Mac OS Shortcuts, disable the Mac OS Keyboard Shortcuts. Then when your mouse is focusing on the guest, the keyboard will be full controlled by guest.
And of course, if shortcuts is not the issue, see the "Two" computers in one in Power user's guide to dedicating USB keyboard.