Re:
I have some of the plastic caps.
The fork has two springs in the lh stanchion, the main and supplementary. The large slotted screw adjusts the preload. You should have about something like 10 to 20mm of sag when sat still on the bike.
The oil is contained in the damper in the rh stanchion, the air is contained [hopefully] in the rh carbon and can be adjusted for pressure via the schrader valve. The Evo3 is essentially a coil sprung fork and the air is only really there as an assistance and to provide further adjustment, hence the low pressure, 60psi should be max really, any more and the compliancy of the ride will be compromised.
If you are over 13 stone then you really could do with a hard coil spring, you can check to see if yours is medium or hard; hard spring will have a bit of blue paint on it.