Brake Piston Heating On Highway

[simpletool]

Hi Guys/Gals (?),

Currently I've got RB74 pads and DBA rotors front and rear on my R33 GTST. I am due for brakes soon front and rear and I usually do them myself.

However lately I have started observing them a bit to see if the calipers need a rebuild.

1. On the track day at QR I managed to boil the fluid with smoke coming out of the front left pads (only once ever). I thought this might be due to that caliper being a bit stuck/grabbing?

2. When highway driving on the weekend I checked the calipers after pulling into a servo (virtually no braking on highway). The front calipers were cold, the left rear was warm/hot and the left rear was warm. Is this normal?

3. When driving around slowly when quiet I can hear the pads on the discs. Is this normal for RB74 type pads?

So do you think I need a rebuild on the calipers? And if so all 4 or the front or the rear?

The car doesn't have any strong swerving under braking or anything like that and no ABS.

Any educated/semi-educated thoughts would be appreciated.