I don't know if pilots are told to be aware of this, but mechanics have to be very aware of the amount of fuel in the main tanks. If you put on hydraulics with the fuel/hydraulic heat exchangers not covered in fuel, it gets overheated! Overheated metal and fuel vapors don't go together. Do not operate hydraulics if main fuel tank has less than 1,8 tons of fuel, or at least keep an eye on the hydraulic fluid temp. (altough I hope you pilots never see 1,8 when flying). Mechanics can have this situation e.g. when we drain fuel to work inside the tanks.
BUT...to complete the story of the heat exchanger... There are 3 heat exchangers, one for each hydr system. Left and center systems in left wing, right system in right wing. The end result of your deicing fluid story remains the same
some more info about the acmp's...to start up an acmp it needs a lot of power. Try pushing in all 4 acmp switches at the same time, you'll find they all start at different times. All pump circuits have time delays of different values, built in for trigger happy pilots who want to save time by pressing all switches at the same time, without knowing they could overstress the elec system.
C2 acmp does not work when only 1 ac bus is powered, for the reason of needing a lot of power. There are situations where both C pumps can run, e.g. on takeoff I believe. Both will be running because in case of 1 engine failure, the remaining engine has not power enough to start up a center pump that would not be running. With engine failure on takeoff you need to get that gear and flaps up as soon as possible (I guess, correct me when wrong), and you need all center pumps running for this to happen quick.
accu pressure: with right hydr pressure on, the accu stores this pressure. With all hydraulics lost, you take the pressure that is sealed in this reservoir. If you don't press reserve brakes that is what happens. Next time when you're on ground with engines shut, check your brake pressure gauge. Shut off all hydraulic, now press the brake pedals several times. You'll see the brake pressure gauge go down. You're tapping off pressure from the reservoir. And suddenly, you'll hear "clunk" and feel no resistance in the pedals. Your pressure gauge will show about 1200PSI. This is residual pneumatic pressure, not hydraulic pressure, you've lost all your braking by now. This happens after about 7 brake applications. Now push the reserve brakes switch or the right acmp, and see the indicator go up to 3000 again. Make sure the wheel chocks are in place however, you don't want to have a rolling brakeless 757. The parking brake will also use this accu. There is also a lot of misunderstanding among pushback drivers. When they see the red light at the nose wheel they think parking brakes are set. But when the aircraft has been parked for 12 hours, all accu press is lost and parking brakes are NOT set, even if the handle is up and light on.
regarding antiskid; in normal and alternate you have each wheel in the system, in reserve you have 2 wheel pairs, on accumulator there is no antiskid.
That's more than you pilots should know, if you want to know more, get yourself an overall and some grease
edit: another one for you drivers; why do we need to put the EDP switches in on all the time, even when engines not running on ground?