Want Factory Shop Manual for Comet 3081 W

I just purchased but have not yet collected a 30" cutting-swath 8-horse Comet 3081 W. I prefer having access to Factory Shop Manuals for equipment I own. Snapper.com web site allows downloading this model's Owner's Manual and two different Parts Manuals. I've downloaded them. But I still want access to the Factory Shop Manual's content with all its suggested procedures. I'd be satisfied with either electronic form or a hard copy, but a lower price would be better.

I have seen Factory Shop Manuals offered for other Comet models like the 306X series. Are they so similar that for almost all practical purposes, a Factory Shop Manual for one Comet can equally well guide maintenance and repairs on sister models?

Can anyone identify this Comet's production year of by its 82087997 serial number? If so, what year was it made? Its 8 horsepower engine was made by Briggs rather than Tecumseh. It has bicycle-like steering handles rather than a "butterfly" loop or steering wheel, chain lift to deck, wide rather than narrow rear tires, a large fuel tank located left of the engine rather than directly behind the seat, and an automotive-sized battery under the seat.

I expect to repaint it. Does any vendor sell decal sets for older Snappers like this?

The owner's manual suggests changing engine oil every 25 hours. That seems an extraordinarily short interval to me. Have owners who used these machines in commercial service found longer oil-change intervals imprudent? Wouldn't being required to change oil after every 3 long mowing days have made these "commercial grade" mowers unacceptable to commercial users when they were new.

What is the smallest tree trunk diameter a 30" cut Comet can mow against with a single pass?
Thanks for your help,
John