Is there any real need to remove the hitch from the bed of my truck? If not, shall I spray lub the whole hitch? With what?

You can remove the 5th wheel at any time. Depending on the rail system you have however, the rails may or may not be permanently attached to the bed of your truck.

Your fifth wheel hitch should be lubricated and checked before each trip using a lithium grease. Lubricate all pivot points where the hitch head moves forward, behind and side to side. If you have a slider unit also, this should also be lubricated.

A King Pin Lube Plate is recommended to prevent metal to metal contact of the king pin on the fifth wheel head unit. No grease is required if you are using a lube plate.