OK,
Thanks for the pics it appears to be in decent condition - a couple of things:
There should be side sheilds on both sides of the engine (under the white side covers) that direct the cooling air over the fins on the head - w/o these it could overheat longer term.
The deck - I would grease the heck out of the spindles (if they turn freely) then do a wire brush/sander on the deck and prime/paint - it will look like new.
Rear axle / hitch plate - its usually attached directly to the AL transaxle and this is known to pull out if pulling towing heavy loads (ask me how I know
) So if you go on line and find a hitch plate - there is one here
R.F. Houtz & Son, Inc. - Product Display This bolts onto the main frame left and right and is 1/4" thick - it is stout.
This is the best solution for the hitch..
For the engine oil drain, its a 11/16" I think and its up under the frame middle of engine plug on the bottom - you can feel it with your fingers.. I use a deep well socket to loosen.
For the transmission you can either pull the rear plate (if its leaking) and drain and clean it out, or there is a plug in the front bottom of the transaxle on the left side (from the rear) that I usually drain the tranny.
Refilling - its a PIA to get 7 quarts back thru the small fill port, but what I do is a medium sized funnel fits tightly inside that fill port then I wrap tape around the funnel and the metal top and slowly pour it in. Watch out as it likes to "burp" oil as the air escapes.
For paint, TSC has inexpensive white and yellow paint too.
Good luck.
Carl