I'm surprised that you have one of those on your F150 from what I recall they were installed on E150 vans and I believe Limos. I am thinking of a long aluminum piece that runs the length of the block with the filter at the rear correct? Yes the engine mount has to be removed but after that there are only a couple bolts holding it on, two 13mm I believe and of course the four 10mm bolts at the front of the adapter itself. Yes there is a gasket at the adapter behind the four bolts that may be giving you the leak problem. Yes drain the coolant first and you will have some minor oil spillage as well. Take care.