You got it.  To do otherwise would invite an air pocket.

The proper coolant is gold, and from Ford goes by the part number VC7B.

I've got a '99 F-150, and I took mine to the dealership earlier this year and had them do a coolant flush for me with some sort of machine. Granted, I overpaid at $99, but at least they were the ones who had to figure out how to do it right.

Approximately 20 quarts.  19.8 quarts for a 4.6 liter, 20.6 for a 5.4 liter.  New body style truck, right?  It's not a Heritage model?

The "overflow bottle" which you refer to is a "de-gas bottle / tank".  You will notice a large diameter hose at the bottom unlike the old overflow bottles.  This is a direct fill to the radiator.  

De-gas bottles are used on closed cooling systems and this is the proper fill point for these types of cooling systems. We use a vaccum fill tool which vaccums all of the air from the cooling system.  Once the cooling system is empty and in a vaccum, a valve is turned which then introduces the coolant into the cooling system without the fear of under or over fill and air pockets.  If you are doing it at home you can add coolant to the de-gas bottle, give it time to work its way down into the block and radiator while slowly filling the de-gas bottle as the cooling system accepts the coolant.  Once no more can be added, start the engine and let the engine warm to the point that the thermostat opens and top off the de-gas bottle to the proper fill point which will be indicated on the side of the de-gas bottle.

Shut the engine down for a bit, let it sit and the system will usually burp itself.  Re-start the engine and run up to operating temp and top off as necessary.  You might have to do this two or three times.