The Bowden cable adjustment is a lot easier to do - you just reach in there and turn the adjusting nut either by hand or with an open end 13 mm wrench if it doesn't turn freely. You want to turn it away from the end with the cable. It should hold the car in gear longer under partial throttle. The modulator valve adjustment is best done with the car in a lift. My mechanic started removing the cap but had trouble getting it off so I held off on it and haven't made any adjustments there all this time. The cap can break easily so it is best to have a replacement handy as you don't want to leave it open ($2 part). On PA_Joe's note, from what I understand, there is not enough of an appreciable effect if you just turn the cap even if you turn it all the way. You have to take it off and turn the key adjuster inside. Look for Steve Brotherton's posting on this - do a search on "flaring".
I have been watching temps very closely from the start and in anticipation of summer I changed the thermostat last week. I also have the resistor mod
for the aux fans which keeps temps under 100, even with AC on in stop and go traffic.
I had that brake light problem and it drove me crazy for a while until I caught the third eye not coming on when the warning indicator came on. It was intermittent which made it hard to diagnose but replacing that bulb took care of that problem.