BlazingPedals

Cratecruncher (and anyone else,)
I got my seat cushions from Don 'Airxxxwolf' Smith. He sells a lot of them for virtually every hard shell seat made, I think. They are cut and routed from zotefoam, which is a closed-cell, dense foam, and is very light. There are two thicknesses, 1/2" and 3/4". The chevrons cut into them don't provide much if any ventilation but they help with keeping the rider from sliding. He offers colored inserts that pop into the chevrons, at a slight upcharge. You can contact Don at airxxxwolf (at) yahoo (dot) com. He will need to know what brand and size your seat is.

I ran with my chain 'dropped' for many years. My aftermarket carbon fork is narrower so that it is no longer in the 'dropped' chainline. That's probably why yours has an aftermarket fork too -- the OEM fork is asymmetrical like a lowracer fork, but it's beefy like a BMX fork. I finally decided that the dropped configuration was really no faster than stock, so I returned it to original. I really enjoy the maneuverability this way.