First of all, based on the layout you describe, you're never going to
achieve a 100% no-snow goal here. But:

In most locales, a judge will enforce civil trespass laws to stop someone
from introducing any substance or object onto a neighbor's property.
Trespass does not apply only to the unlawful entry of people. However, it's
usually enforced for such things as pesticides, or a neighbor's kid's
baseball repeatedly coming too close to you while you're at your picnic
table. You're not likely to get anywhere with the police in terms of the
snow. So, find a happy medium he

1) Tell him to aim the chute lower and stop hitting the house. Offer to show
him how some of the controls work on the machine. Explain that if he can't
manage this, then you assume he's prepared to pay for any damage to siding
or windows if a rock is included with the snow. He should be particularly
alarmed with the siding issue because you'd want a perfect color match for
the repaired section, right? If the siding's old, that could mean redoing
the whole house. Oh my. Thousands of dollars.

2) Plants: Do some research and find out if, in your climate, it's a good
thing for your PARTICULAR plants to have some snow cover. Often, it is. If
so, leave the issue alone unless the weight of the snow is damaging
branches. In that case, negotiate. If that doesn't work, call the cops while
he's operating his machine.

3) Your porch/sidewalk: Same as #1. Better aim.

4) Cigarette butts: Buy the cheapest large can of coffee you can find, and a
small bag of cat litter. Use the coffee, or throw it away if it's awful. Put
the cat litter in the can, bring it to him, and tell him to use his new ash
tray. Don't ask. Tell him. If you find one more butt, call the cops.

Beyond this, forget trying to keep ALL his snow off your property. It's not
going to happen. Your only other possible option is to put up snow fence in
the winter. It might be tall enough that his machine won't be able to throw
the snow over it. And, it's cheap & reusable.