All rifle brass is annealed, leaving a dark area around the case neck, but you wont see that on commercial brass because it is polished out. Annealing makes the neck softer than the body allowing the bullet to be released without cracking the neck.
Reloading is part of shooting. All the best shooters at the range are reloaders. Tailoring your ammo to your firearms and large volumes of practice ammo will vastly improve you marksmanship. So if you want to be one of the better shooters at the range, start reloading.
There are no “must” have add-ons needed other than conversions for each caliber you will be loading. Extra tool heads, powder measures, and powder dies (one of each is included in a quick change) are nice to have. Also a spare parts kit can save a reloading session if something breaks.
For target shooting I do not like the way RN bullets rip the target, and much prefer WC and SWC for the nice round holes they make. RN and RNFP are best for cowboy action shooting and even then mostly just for nostalgia and the looks in ammo belts. You can use data for 158g RN for your 160g RN...
That is really a good question. I think I would size on a single stage then run them through the 650 to complete.
That way you could run anything you can get a shell plate for.
I bought the complete priming assembly so all that is required is to replace the punch and 2 screws. No fiddling with small parts/adjustments required. Cost a lot less than a second press, and frees up bench space.
https://www.dillonprecision.com/xl-650-large-priming-system_8_116_23809.html
There is no more versatile powder than Bullseye, it can be loaded in 25acp up to 44mag. Data for a 115g jacketed bullet can be used for JHP and JSP and FMJ, of any manufacturer. This is why we have and use a starting load, and work our way up from there. If we were to use the exact same bullet...