Question for knowledgable Harrier person: what is the standard procedure for a ski jump takeoff? Set jet exhaust horizontal, and mash down on the rudder pedals/brakes as the engine spins up to X percent of nominal full throttle? Do the brakes hold to 100 percent standard power?
Until one of those turns up, you'll have to make do with answers from me. Your second question is easiest - no, they do not. Or rather, the brakes might but the but the tyre/deck interface will not. Only the main gear has brakes, so given the the nose-wheel and outriggers have about 1/2 the aircraft weight sitting on them and that even the heaviest ever Harrier II launch was at rather less weight than thrust x 2, there's just not enough deck friction available.
You might want a proper pilot for SOP, but in terms of throttle/brakes after all the tailplane trim, duct pressure and IGV checks (and lots of other checks too, probably including seeing if anyone is showing you a green flag) it will be held on brakes at an above-idle but still not very high RPM with nozzles aft, watch the bows for deck motion in the unshakeable belief that ship motion is in some way predictable and that trying to time it somehow gives better results on average than just not bothering, then at an opportune moment slam to whatever full throttle gives (no dainty setting, just slam by feel to the full-throttle stop) and release the brakes when the jet starts to move as the RPM is racing through high numbers (typically in my experience after dragging the main gear for about 5ft). It may be a turbo-fan engine but it still spools-up very quickly between the previously referred to above-idle RPM and max.
Hopefully if that's too far away from the truth a Harrier pilot will be along to correct it. I can't be expected to remember everything that happened on ship trials.
Many years ago before Sharkey got his hands on a SHAR it was felt that the SHAR might want a hold-back device. The pilot could then wait until the engine got to 100+% Nf, have a leisurely check of everything and then go when happy. So way back then "my" jet was given a little button on top of the nozzle lever for commanding hold-back release (it never to my knowledge got the rest of the kit though), which lives on to this day in a certain flight simulator if anyone ever finds themselves in that sim and wonders about it. I don't know when the decision was taken to not bother with it for SHAR. Maybe someone mentioned that it would cost money so it just got overtaken by events.