Re: high frequency Powerlifting/upping volume
While I'm not a powerlifter, as long as you can recover adding volume can be done.
I was working out 2x a day 5 days a week and saw great gains at age 31. I had my food intake dialed in and I made sure to get 7 hours of rest during M-F and a little extra on the weekends.
As far as a program there are tons of options out there program wise that work.
Westside and Wendlers both come to mind as both allow for adding volume and focus on the big 3 lifts.
Often what most guys will find is that they need to look for those weak links in their lifting. Accessory lifts can do wonders in helping to get max weights going back up. Sometimes the best adding of volume comes from the accessory lifts.
You could also add Joker (Wendlers newest stuff) sets into your days when you are feeling strong. The perk of basing all lifts off of 90% raw is that some days we feel amazing and we can add that volume safely and get benefit from it, and on the days we don't we skip it.