160 is far too cold, stay at a 180 or stock thermostat.
To my knowledge you can still run headers in the park ave's, I'm not sure how much if any modifications would have to be done.
You might be able to run that 3.4 with a plog/downpipe, you'll just have to see what the car thinks of it. The PCM won't continue to advance the timing, its always at a set number for WOT that it tries to reach. To me anything past a 3.4ish pulley you'd need headers for the added amount of air you are wanting to flow.
I think you should choose one or the other on the I/C and cam idea. A intercooler can really help but they do have draw backs and can be a real pain in the ass sometimes with the amount of parts you need to run one.
