I'd like to know if the following sentences are possible.

1. He drove over the ramp (I can't find an example). He followed the signs to Milan and then left the motorway.
2. He stopped at the tollbooth and inserted the money in the ...

1. Usually, we drive up a ramp or down a ramp. Or, if someone is driving on a freeway, you could say he took the off-ramp -- or the on-ramp if he's going onto a freeway.

2. ... and inserted money into the pay slot (or threw coins into the bin).