Well, here is the link for the questions you have about registering your new car in MA. Sounds like a bit of a hassle.
In Oregon were I live it was a lot simpler. The dealer wants to make sure I have insurance before I drive off the lot so he calls my insurance agent and gives the VIN number of the car, the agent then gives the dealer a policy number and done, I am insured. They may fax some paperwork to each other too, I don't recall. Other insurance details about levels of coverage, deductibles, etc. I can change with the agent later.
As far as registration and license, the dealer just adds those fees to the normal paperwork and files the registration form with the state. I don't have to go to DMV at all. And the dealer is not allowed to make a profit off those fees so there is no real advantage to my going to the DMV myself. If the registration is $80 and $15 for a temporary to stick in the window until the plates arrive, that is what is added to the paperwork. The dealer calls me when my plates come in and I go pick them up or they put them on.
It will probably go smoother than it sounds, the dealer should be able to handle most things for you. Maybe the insurance stamp and signature is just a faxable form.