In B vs B i always like to raise a little more than min to compensate for playing out of position, even if min raise has been my standard open. This flop seems to hit a lot of his calling range and with only a backdoor flush and gutter i think a fold is fine, especially as his re-raise was a full 3x leaving himself only 1800 behind

As played this is an easy fold. There are lots of possible hands that he could conceivably raise with here, and your just not going to be shown complete air very often at all. Personally I find a limp-shove line preflop in this spot works quite well, especially if the BB is the type of player who likes to pounce when weakness is shown. And if they just check then it's not the end of the world, you have a bit more room to play post with the pot being a bit smaller, and your hand is disguised.