Newbie queries on Pre4

[LesleyEA]

Hi, I have just taken possession of a prebuilt Pre4 it doesn't have any +/-, left/right indications for connections to the rear panel and the manual is silent on this - can you give any advice.
Also there are 2 sets of outputs one being recessed - is there any significance in this?
There is also a chassis earth on both preamp and PSU but again no advice as to if this is optional or essential.
Any help would be very gratefully received.
Many thanks.