The Rifles Only FTW sling is very well designed and well made. I used mine at the Raton Sporting rifle match. I think it would take a lot to break the polymer buckles they are rated to 500 Lbs.
Your order of operations might need to be adjusted. Annealing before cleaning will bake the carbon in your case neck. Consider depriming; cleaning in SS media; anneal; FL size then trim with the WTF and so on.
I shoot with guys who clean hard after each and every session and with another group that never clean. I think there is a mid-point to be found. I like the Boretech carbon cleaner.
Trimming brass with a hand crank lathe type trimmer takes quite a bit of time. I use the Forster and though it is dead nuts accurate it takes a ton of time. I am looking at the little trimmer as an alternative.
Why not use the top of your scope base?
Have you seen the Badger scope tool? It is a rail milled into a triangle base with a built in level and threaded feet. I am a tool junky.