Wow. That's a pretty huge question in a relatively short post. It would probably be best to refer you to the Long Range Hunting Basics thread. The same information applies to long range coyotes but the coyotes are even smaller. Once you remove the hair from a coyote, the target area is only about five inches deep. The other problem with coyotes is that unless you have a carcass to shoot them off of, they rarely stop. It ends up being a two or three person game with someone ranging or running ballistics and the other dialing and shooting. Harder than it sounds at first.
The mildots are probably your best bet of the optics you mentioned but I prefer to use target turrets and dial for anything past 300 yards. Doping the wind will be the nemesis of your LR shots. You can use a wind meter to help but a lot of it will still come with practice. The high ballistic coefficient bullets will keep the wind deflection to a minimum if your barrel twist will stabilize them. The last thing for coyotes and cows is that a more fragile bullet will kill them better and won't bounce around the neighborhood as bad (which they can even after hitting a coyote).
I like the way you think, though. You may eventually find yourself on a long, expensive road of rifles, reloading and optics but it will be a fun road!
Good luck. It sounds like you've got a great place to get your LR shooting tuned up!