1. The heavy stutters when, after selecting gate/parking during taxi-in, the ground vehicles appear at the selected gate/parking.
They are not a problem, because they last only a second and, of course, it's nothing we can control, it's just that creating an object *does* take a little pause.
2. The green message "a marshaller has been dispatched onsite": I selected verbosity at minimum but that message still appears and I would like to have the possibility to remove it as well
As explained, many times already, messages are there to clearly indicate that something is happening, and several times we had support issues due to the fact the user believed there was some kind of problem, but the problem was that he simply turned off all messages, so it appeared the program "didn't do anything".
We'll check why the marshaller message is not linked to the verbosity slider, anway.
3. After parking, the marshaller goes away, while he should come beneath the plane and connect his headphones with the cockpit
That's of course one of the many animation that might be added, nobody really asked for this before.
However, since the marshaller doesn't to anything more after you parked, that animation wouldn't really represent anything, it might connect the headphone, but then ? Staying there with the headphone connected for an xxxx amount of time then going away ? How much time ? If use other add-on products that simulate the subsequent marshaller dialog, GSX should might not be in sync with those so, making something that would work equally with FSX entirely default and with possibly many different other add-ons, could become very complex quite easily, and if GSX started to reproduce the *whole* procedure, you would then ask for a way to turn if off, because you might want to use that other add-on instead.