More categories is definitely coming, we could see a little bit in one of Hugo’s sneak previews:
https://community.monzo.com/t/breakdown/9589
Managing payees is work in progress. I heard it either on Open Office, Meetups or some other channel. I don’t remember the details (or how official it was!), but we definitely won’t be stranded with manual fill for long time. 
It was clearly remarked that Preview is not a complete app, so I’d like to advise to stay away from “we need this functionality” wagon and wait until Current Account is released properly. 