Definitely drop the night feed, he’s not far off 1 when milk becomes a drink not a food so he really doesn’t need that night feed.
Reduce it gradually every 3rd night and see how it goes. Don’t cave and offer more if he protests though, stick to it. If you don’t want him in your bed, now is a good time to keep settling him in his cot too. I wouldn’t worry about him disturbing his sister either, she may well sleep through. I remember a night when my DD had a stomach bug, we were up with her every 20 mins for a few hours. She shared a room with her brother at the time and he slept all through it...!
Laura