hey man, i don't know your technical skills but because you know about the drain plug you must be okay.
i am a mechanic and word to the wise don't pull the drain plug. it is alot easier to just pull the lower rad hose.
also go to chrysler to get the fluid, it is benz fluid and they will tell you how much you need.
finally don't be scared about air locks, put the heat on (when you have heat you don't have a air lock) and just wait for the fan to come on and your done.