hi,
It is clear that descending right on the track in the airway is a way to meet somebody during the descent. But if you had a direct clearance offtrack you may stay on heading since you're supposed to have a unique track (actually some direct tracks are sometimes a kind of unpublished airways). the behavior is finally to avoid any congested area. TCAS display could be a useful tool to helps choosing a track
always breaks ON after rejected take-off. you must analyse the situation at that time and get rid of any movement of the aircraft to do it. forget the brakes blockage. you will think of it after you decide to not evacuate.
let's consider you have pure crosswind. think of a big airplane to park cross on the runway (time to do it) and then no vehicles are able to circulate on the concrete that might not help for fire (and the rest) assistance. thus stay on the centerline.
to finish there is a new ICAO phraseology for the TCAS, from nov 2007.
search for PANS-ATM Amendment n°5 on internet