[akruppa]

It does not save the highest B2 value tried so far anywhere, you'll have to specify the B2 range you want to do manually each time.

Where exactly the factor p with largest factor in p-1 around 2.5e14 will be found is hard to tell, due to the Brent-Suyama extension.
With -power 2, it will be as you suggested. However, if the B2 value is much higher than 2.5e14, it might be included as a composite value, i.e. if q*2.5e14 is in your B2min-B2max range for some q that does not divide d1*d2.
With Brent-Suyama, all bets are off... the missing prime in p-1 might be included pretty much at any time during stage 2, if you're lucky. But it is still true that if the missing prime is in B2min-B2max, it will be included in any case, and the factor will be found.

Alex