I found mine on eBay and then added upgrades. The ponsness Warren website is easy to follow and they promptly send parts with very clear instillation instructions. It is an awesome machine which makes a great round.
Depends on how much you are planning to load. The simplest with low cost is a MEC Jr. They are cheap
enough you an buy one for each gauge. I finally settled on a progressive press. I have a Ponsness Warren which I really like. I only load 12 gauge.
I have used both styles smooth and checkered. I much prefer the newer checkered grips they provide an excellent grip. They have improved the checkering pattern on the newer style grips. Your hands do not slip.
I shoot 357 Rugers OMV with 5.5 inch barrels. I prefer the longer length. They are slightly heavier and I can stay on target. Although part of this equation are the load characteristics of your ammo. I use 105 grain bullets with 2.9 of Tite group which has minimized my muzzle rise. Also style of shooting matters as well. Eg, duelist vs gunfighter vs traditional.