I would try to isolate the blower motor power connection, disconnecting anything from the motor and jumpering 12V DC directly into it to see if it will run when power is applied. That would rule out a bad motor. These are good places to start.
there must be some compression if the cam shaft is turning
indicates that the belt has broken or stripped off
I say some compression because if the cam shaft is turning then at least 2 pistons will be recording a pressure however low it may be
if as you say there is no compression ( a compression test has to be done to determine that) then that means that the valves are not opening or closing to get a compression stroke
Unless the battery charger is a high power over 12amp hours charge rate you should be looking at 12-18 hrs minimum as the battery is a 78Ah unit for the 2 litre you may get of with 6 hrs but that may give 3-4 start attempts before recharge required
plastic radiator tanks crack and fail with age and a radiator that is 11 years old is a candidate for failure
Unless there is a really bad failure ( bottom tank blown off under pressure ) the top tap will only leak under pressure and it is normally around the radiator hose section or along the area where the metal tabs attach it to the cores
I would suggest that the shop is reasonably accurate in their diagnosis ( would show up under a pressure test of the cooling system) so a new radiator would be in order
the only way that the seal pops is when the piston comes out the end of the cylinder that indicates that the installation of the clutch kit is incorrect and the throw out arm is not in the throw out bearing carrier properly
regardless of makes , if the clutch kit is made for that vehicle it will fit
Yes, there is a neutral safety switch on the transmission, but it is expensive. Check to see if it is adjusted properly. You can also remove it and test it with an ohmmeter.