New daily driver questions

[CoBeerToad]

I've recently took a job that requires a 45 mile commute from the south side of Chicago to the north side. I've only been there three days and my commute takes (so far) between 1 hour, and 2 hours 10 minutes. I like driving a manual, even in the stop and go traffic and I think it makes me stay more aware of my surroundings. However, I have some questions relating to what is the best style of driving to maximize gas mileage and not beat up my car.

1. If I'm driving full speed (50-90mph) and I see brake lights ahead sometimes I'll just press in the clutch and coast until I know for sure if the traffic is actually slowing or if they are just reaction brake lights. My question is while driving at these speeds and I press in the clutch of course the motor slows to 800-ish rpms. Is this bad? The only part I question is the cooling system. Is there something I'm missing or is this acceptable?

2. In stop and go traffic sometimes traffic flows about 5mph. 5mph, even in first, is less than 2000 rpms. Is it acceptable to ride along at that speed or would I be best served by running in first and then pressing in the clutch and coasting and repeat?