I bought 2 sets of the millet lows for less than one set of "higher end" rings. I use 3 rings on my scope. some would say pay more but these things seem real nice beefee too
the 12.5 vs 25 is a product of being a 2nd plane reticle. most 2nd plane scopes dont have the benefit of having full mil and half and yes it does help with ranging. I was able to use it to accurately range a deer at 1440.
most on here would agree that moa to moa or mil to mil is easier than mix and match
dont be afraid to adjust. the scope hase come up hash marks so it is easy to return to 0. with all parallax even highend scopes do not trust the yrd marks (many just have hash marks) this is not a focus knob to tell if parallax is set right while looking threw the scope move your head back and forth to see if the cross hairs move , adjust until they dont. most scope complaints and problems with 0 stem either from this or mounting
no see above
find ammo that shoots good and practice. use a ballistic computer to get close than build your own dope card. I site for MPB which is around 27 to 37 yrds depending on load and scope height. this makes 0 again at 250 to 300 yrds ( 300 on most of my guns) and 1 mil high at 100 ( aballistic computer can help you with this)
almost any good gunsmith will install a break. you can order many types on line most here seem to like Viase and Mussle breaks
Hope this helps