Super easy, there is an oil drain plug on the bottom, no oil filter on Apollos, just get a new crush washer for the oil drain plug. Best to measure the old one and order a 50pack from amazon they are like $10 for 50.
Chain is easy too, just jack up the quad make sure in N and spin the tires while spraying some chain lube on the chain. Best to spray downward into the chain as its returning to the rear sprocket. Do two full rotations and that will be plently. Not sure if your machine has a paper stick air filter, but if so consider going to a two stage foam filter....like a UNI also avail on Amazon.