Audi 4.2 Quattro Sport Fault codes

[J33RCB]

Hi all,
I need some help please,
My car is throwing EML fault codes.
I know the codes but need help interpreting them and the solutions,
They are related to Long term fuel trim (too rich) P1137/ 17545.
Two questions arise from tonights computer session,
On Both banks the O2 sensors one and two are active, three and four are dormant? is this right?
What is the EVAP? is it the same as an EGR?
I do nt want to take my car to Audi (long story) but would welcome any advise or specialist recommendation for Northants.
Thanks in advance
Jeremy