1 and 2 are related. As well...I'd like to suggest not shifting the car in/out for coasting. The torque converter will allow you to coast almost as well. My reasoning is the forward band in the trans is known for breaking. When you go from N to D that engages the forward band, in out in out in out... is releasing, engaging constantly. Doing this you have a better chance of breaking the band. When you break the band, you find out, it's the second piece put into the trans case and a full rebuild or different trans is costly.

3 is likely a sensor. Are you checking the overflow or radiator?