If you take the Driver's side interior door panel off, there should be a black module with a white sticker on it located near the back (near the catch) of the door. That sticker should have the keyless entry code on it.
The Marquis does not have a standard code. A dealer may be able to supply the factory code for the exact car, unless the code was owner changed.
Usually on one of the Trunk Lift Rods. If you can't find it, a dealer can look up the Master Code for you.
take it to the dealer
You cannot reprogram it. A dealer can get you the Master Code if you've lost it.
Either go by the Mercury dealer or call with your VIN None to be found.
ask a car dealer
Most of the time all you need to do is replace the battery. If it doesn't work after that, you will need to take it to a dealer.
No, it has to be the right one. Take it to a dealer or a locksmith that does remotes.
The dealer should have that information. Also it may be in the owners manual. If you don't have one, try MOTORLIT.COM
Yes, this can be done by a Ford dealer.
One in the trans and there may be a filter on the cooler line if it had a trans replaced at the dealer or had a dealer reman installed.
there is a "wallet card" which has the code on it, if you do not have this card you will need to bring the car into a Mercury dealer and they will "plug it in" and retrieve the factory preset code.