Hello and welcome. Both triggers would be good, but the Jewel gives you much more adjustment. For a field rifle you may not want to go under 2 lbs for your trigger pull anyway so the Timeny may be what you are looking for. Jewel triggers will adjust down to a couple ounces and that is geared more for your benchrest shooting.
I shoot a WSM as well, admittedly I haven't had the opportunity to take game farther than 350 yet, but if conditions are good and the opportunity presents itself, I'd feel comfortable taking white tail out past 800.
For ammo, if you don't want to start loading just yet... you would be fine with either 165 gr class ammo or 180 grain ammo. You just have to try some stuff out. If I had to test I'd buy a cheap box of Federal 165 and federal 180's and see which one shot better. Then I'd take the winning weight and buy a couple different brands of that weight and test them. A boat tail is preferred, but not necessary for just 500 yards. Better to hit consistently and have to aim a little higher than to have a super flat shooter that throws buckshot.
If you want to limit your testing to save money, one of the first I would try would be federal premium vital shocks Nosler BT's 180. IMHO, the Ballistic tip is an excellent choice for white tail but the 150, and even the 165 grain will be going a little fast and make a mess of the game at less than 100 yards. The Accubonds are very good (I handload 180 ab's for mine and have very good luck) but they are pretty expensive to buy factory loaded.
Now, if you have the urge to start a potentially time consuming and very addicting habit/hobby, start buying a press, dies, and other tools for handloading
Good luck, Mark.
Also, A good drop chart may be all you need, rather than the M1 turrets. The turrets will just make the dialing easier. A good ballistics program is needed, and a reliable velocity to start with. Exball is excellent, but I use the FREE one at http://www.eskimo.com/~jbm/calculations/traj/traj.html
You can not go with what is posted on the web for your velocity. every rifle is different and generally published velocities are higher than what you will actually get. You can either use a Chronograph to test the load, or you can get pretty close by shooting at 2 targets with a known distance (100 yards and 300 yards for example... the farther the better) and play with your ballistics program to find the velocity. However, no matter how good your ballistics program is, you ALWAYS have to test your drop charts on targets. Your scope may or may not have true 1/4 IPH or MOA (inch per hundred or minute of angle) adjustments, your Ballistic coefficient may not be right on... the list goes on. Point being that there are lots of variables and consistency and verification is/are the name of the game.
OK, I'll stop rambling now...lol