Will it start on brake cleaner/easy start sprayed down the intake?

Other than that it needs fault codes reading, fuel pressure testing and so on really.

If the car has just one ECU yes it controls the injectors/fuel pump and all the other gubbins, you get a 5 volt feed to the injector then the ECU grounds the injector to activate it.

Early TDCIs had 2 ECUs, one to control the injectors, other did the rest of the engine control functions.