Oh, where to start?
Check all your batteries with a meter FIRST. That will give you a base line.
Were it mine, I would put an old dumb charger on each battery to see if they come up to spec first. If they do, go ahead and plug her in. Don't = replace.
Next, give your hot water tank a good vinegar bath and pull the blow off valve and stick a water wand in there to rinse out the calcium (white flakes), then bleach the entire water system. Youtube is your friend.....
Re the chassis, a grease job oil change with filters should do it. Check the Tx and diff fluid levels too. So many new owners don't.
Mike in Colorado
2004 Fleetwood Pace Arrow 37c, 8.1 gasser, (Jezebel) Ultra RV ECM / TCM, plugs wires, and rear track bar, PPE deep Tx pan, Bilstein's, Sailun's & Sumo's all round, pushed by a 2002 Grand Caravan, on a Master Tow Dolly.