(1) Rakes snow from his lawn into the street, and then hoses down the snow in the street;
(2) Washes mailbox with a bucket and rag right at dusk, and pretty much peers into other houses for 10 minutes while he pretends to wash this mailbox;
(3) Mows his lawn, then blows it with a leafblower, then weedwacks it (the entire yard, not just the edges);
1-3 are silly stuff that lots of neighbors do and are harmless to you. Forget about this stuff. But do close your blinds if you can see in at dusk. ;)
(4) Mows and fertilizes up to my driveway (a good 10 feet onto my property)...I asked him to stop and he said "I've been doing this since 1978;"
Tell him to stop if this activity is doing any damage to your property. Tell him "You do not own this part from this point over, so you need to stop doing any further lawn work in the future. I don't care if you've been doing it since 1878, I am telling you again to stop mowing/treating my yard because I do not like it and it is damaging my property."
(5) Any time I go outside he comes and talks to me about how much he hates the other neighbors, how things used to be different, etc. All of these conversations do not end unless/until my fiance comes and asks me for help (he talks 95% of the time);
Wear earbuds even if you're not listening to music so you can point to them and just wave and walk on by. Or take your phone out with you with a bluetooth headset and point to it and say "un huh" into it a few times so all you have to do is smile and nod as you walk through. Then go about your business. Or simply say "so sorry, don't have time to talk right now" and move away from them even if that means he's talking as you leave.
(6) Edges/trims my mailbox;
Same as #4.
(7) Puts dirt and the debris from the curb and sweeps it into my yard.
Same as #4.
What do your neighbors do about him? Might want to ask them how they handled him? He sounds like he may be an old guy that hasn't many friends and is obsessed with yard work and is doing stuff on your yard because it's not up to his standards and he likes his area to look just so. I'd go talk to the people that live on the other side of him just for giggles to see how they've handled his overactive lawn grooming.
But mostly, I'd just ignore him. If he wants to go crazy trimming and edging his yard and into yours, then again, as long as he hasn't done any damage I'd just try to let the annoyance part go. The only way I'd confront the guy is if 1) he damages anything; or 2) he tries to plant or build anything that is not mutually agreed on, because in many states, land usage can be construed as ceding over that portion of the property (my mom had that happen in her favor with a very old house and a common drive, and my dad's house lost about 2 foot of property along one edge because he didn't protest a neighbor having a driveway laid over the property line).
I had neighbors with small kids that for some reason set up their slip and slide in the space between our houses and set their garbage cans out on my side of the yard which is very obviously mine - instead of in their back yard. They have a yard service that mows the side yard like it is an even 50/50 split, but it's more like 20% is theirs and 80% is mine (fence/property lines are obvious), so that means every 10 days our side yard gets a partial cut and edge. Annoyed the ever-loving crap out of me for the first year.
But you know what? I don't give a rat's ass now. Obviously after 13 years here, the kids are grown up and are no longer using the slip and slide, and nothing they're doing is damaging my usage and/or enjoyment of my own property.
Getting pissy with the neighbors over something that is at most annoying is just a recipe for having a very uncomfortable time for the rest of the time you are neighbors. Let it go unless he's really causing damage or hardship. Honestly, you're still a bright and shiny new homeowner so I think you're letting this guy get under your skin way too much. Chill and realize that you will always have the probability of having a kook or crazy person in your neighborhood and as far as kooks go, yours is pretty lightweight.