How many microphone input signals can Steinberg's UR44 handle?

[Maarten Siebel]

1) The front side is good for inputting 4 microphone signals which allow to vary signal strength.  Does the rear side offer the input of more microphone (not signal strength variable) signals?  I do not find info on this in the UR44 manual. 

2) I have two USB microphones available (Rode NT-USB mini & Logic HD 1080 p) but I have not been able to make their signals visible in SONOBUS. Any suggestions? 

Thanks for any help.

Maarten Siebel