In my experience with my babies, the answer to your queries about cluster feeding, dream feeding and waking to feed are yes, yes and yes.
Yes I cluster fed and dream fed to eliminate the 2/3am feed. It may seem like it's not worth it as they seem to take so little when fed so often but it adds up to more day time intake than with regular 3-4 hourly feeds over 24 hours. And yes this is when I resigned myself to having to wake them up from naps. It is soooooo painful to do that but you'll find that they sleep more consistently well once you start to do that.
I agree that if you can be on top of it now it will prevent any AP needing to be corrected later on!
Good luck with whatever you decide to do.... You are doing an awesome job even thinking about this now. I am sending you strength in your conviction with the choices you make as well as I had a really hard time trying to convince even my husband that it was the right thing to do. I read so many chapters from books out loud to people around me to get them on board with sleep training.,., truly infuriating that the lazy b#st%rds wouldn't read even one chapter of any twin or sleep related books.
Fantastic news about the chunk of sleep last night. It really makes a difference doesn't it?! Should help with your supply too