1) It looks like the attacker spent most of the smaller outputs and left the massive outputs alone, the latest version should block those massive balances but I calculated they were able to get away with around 260 million XCN from the smaller outputs.
2) I also want to make it clear this bug has nothing to do with the mini-blockchain technology, the bug in the code was pretty obvious and quite easy to fix just by making some signed integers unsigned. Look at the latest changes on pallas's github to see exactly what we did to prevent this happening again.