You haven't mentioned mics. You may need 2 or 3, if you are playing ; listening with headphones, bare voices won't be heard.
30 sq.m. is a nice size, and while the drum kit will take up valuable space, I think there is room for a couple of practice amps at least. 60 watt with 12" speakers will be plenty. Then the vox can go through the p.a. With the amps spread out, there will be a more spacial feel, with guitar and bass coming from different directions. I also feel that using headphones, especially if you also use wired mics,etc., will end up with spaghetti all over the floor (too many cables).
Ideally the p.a. speakers would be hung on the wall, but then you will probably have feedback problems with mics - if you use them.
Also, a source to play backing tracks (and ordinary ones !) is useful. This, in stereo, will need inputs to plug into - unless it has its own speakers - which CAN go on the wall.
With the recording facility, you can always use the send output from the amps to get guitar/bass signals to the deck.