Flash2001
In answer to 1 of your question's - Concorde used reheat on takeoff to about 1000ft and then again when accelerating to and through mach1 and was again switched off once mach1.7 was reached whereby 100% raw engine power was used - reheat was only needed to get through the high resistance area around mach1.
Mach1 had to be reached or passed by 100miles off the coast, in the UK this was 100nm off the coast at Coombe Martin on the north coast of Devon on one of the SST tracks across the Atlantic -in the USA the accelaration point was just off the coast of Nantucket Island, normal altitude that mach 1 was passed was between 30000-45000 ft it would varie each day depending on the outside air temp.
Hope this answer's a couple of yr questions
rgds
W.G