BU no longer updates the SV implementation. After Feb. 2020 they will stop working when SV hardforks with the Genesis update where among other things P2SH will be removed.
True. If an exchange end up accepting another chain which will later become a minority coin they can loose a lot of money. But I don't see a way to prevent it in an open economy.
Installing two different core node software, and ensuring the balance is the same on both node. If not, cancel the transaction, and throw it back on the user.