Re: 2 part Question.
Accurate's 2005 guide shows 106 grain top end for a 220 in the 300 rum and 106 -111 top end for a 200 depending on bullet. I'd start in the middle 90's and work up till I got to 3000 fps or so with it.
As far as fireforming, more info would be good, but usually ten grains of bullseye speed powder and some farina will blow out most brass pretty well. Small cases (under '06 class) will need less powder. Go light and go up until you've got good form.