I always used Modified or Improved Modified. Take all you have with you and examine all the stages, then decide. You also can change between stages if the distances really vary.
You can use small rifle primers in place of the small pistol primers. I use Tula SRMP in 9mm, .45ACP and .223/5.56. Load up a few and chrono them, usually won't raise the FPS more than a few and sometimes not at all.
Reciprocating is fine, I've used them for a long time and never had a problem with them. Also, if you are trying to save weight, they are lighter than the other.