1. Can I remove the number up the marshaller (photo in the topic) ?
Yes, by unchecking the "Marshaller Distance Readout" option in the GSX Settings.
But in EGLL the Packages and the vehicles wasn't with United Livery. I know the vehicales need to be diffrent.
This has been discussed and answered many times on the forum. The ULD livery is not set by airport, but depending on the atc_airline_codes parameter of the airplane you are flying.
If the airplane lacks the atc_airline_codes parameter in its aircraft.cfg file, the ULD livery will be chosen randomly amongst the ones available for that airport.