The drives are usually quite quiet under light loads,ie dring across a level driveway, but can groan or moan loudly under a heavy push, ie filling the bucket with gravel. The motor should stall or you should run out of traction, the machine shoud not just sit there doing nothing.
I not sure exactly what you mean by chatter, but i think if one of the wheel drive chains was slipping over the teeth on the sprockets you would know something was definitly wrong.
Hydraulic and chain case oil should be changed every 1000 hr. Don't forget you hyd filter(s)
You can drain your hyd tank into the chain case if you like to re cycle your oil.
Also don't be to surprised if your chain oil has some water contamination from a poor gasket on the covers over the chain case. (milky color)
maxxwedge and others have manuals on ebay but some of the dealers will sell them to you for less then some on ebay want for them. Also parts prices are set by the dealers and can vary from store to store
Tazza will likely give you a few pointer on some hidden strainers/filters. I don't recall the details as I don't have this particular model
I'm sure you will enjoy it, some feel this is the best boccat ever made
Ken