1) It depends what you want, a 1.073 beer could make an excellend sour (I'm about to do a sour tripel).
2)I'd pitch the dregs in directly along with a healthy culture of a primary Sacch strain.
3) Should sour fine, 30 IBUs will stop many strains of Lacto, but the Pedio will be fine. Bitterness and sourness can clash, but after a year of aging you'll be down to 15 IBUs, so no issue there.
Also a note, I did a Hennepin clone from BYO years back that called for 1 oz of dried ginger, waaaay too much. I'd use fresh, or if you go dried back it down to a gram or two.
Hope that helps, good luck.