Is this the intake manifold page you have seen?
http://pics2.tdiclub.com/gwillie/VW/Sballintake/INTAKEMAN101b.htm
http://pics.tdiclub.com/gwillie/VW/Sballintake/Intake_Manifold_Cleaning.pdf
The thermostat on a 1.9 TDI 110 Toledo is in the block. Take off the pipe that connects to the radiator bottom hose and you'll find the thermostat behind it.
However, the sensors you're talking about aren't anything to do with the thermostat, which is a self-acting control element with no electrical connection.
The sensor in the engine coolant radiator, assuming that is what you mean by "the front radiator", is a thermoswitch for the radiator fans. However, I'd identify the "front radiator" as the condenser for the air conditioning coolant circuit.
Right hand side of the engine block half way down describes the position of the oil filter housing, to me. The sensor connected there is the oil pressure sensor.
On the right hand end of the cylinder head there is a piece of coolant pipework which has the coolant temperature sensor in it.
I'll need some more detail to identify these sensors with any more accuracy.