Post a log from your current tune, 4th gear pull ideally, as described in my thread here:
https://f30.bimmerpost.com/forums/sh....php?t=1732327
I have no doubt that that your custom tune is nearing the HPFP limit if you are running E30 since the MHD stage 2+ OTS E20 map is near the limit of the stock HPFP for me when i run E30.
A HPFP in itself will not add HP to your car assuming your stock HPFP is not crashing on your current tune (very unlikely with a custom tuner since they would tune around it). Of course, adding a HPFP will allow you to push to higher boost levels and/or higher ethanol content, the latter allowing for more timing, both of which can make more power. So you unlock the
potential for more HP with a tune revision but do not immediately gain HP.
The point above about cold weather is less relevant if your tune is load based as the MHD OTS maps are. And in any case, your custom tune should be designed to work in any ambient conditions and not crash in cold weather or suffer from poor timing in hot weather, etc.
As to the 2nd question, are you talking about the two they just posted about for flexfuel integration?