Practice a LOT....and then just do what you do.
Also...7-12 songs in one day may be pushing it, unless you just want a typical demo of a live band rehearsal.
I think this should
really be taken on board.
Most first-time bands spend half the day setting up and enjoying the experience of being in a studio, then the other half try to cram in twice as much music as is possible.
The result is almost always too many compromise recordings.
Aim for 3 or 4 solid belter tracks. Rehearse them until the whole band can play them flawlessly live three times back to back.
Have your other stuff rehearsed just incase, but be in the frame of mind that you probably won't need it.
Allocate a GOOD chunk of your session time to listening, and don't chat through it.
Most young bands go home not having heard their record. Then the phone calls start. "Can you turn up this and turn down that".
Listen on the day!!
Record your rehearsal with a phone or camera or something. Of course it will suck, but it will let you know what to work on.
There's no point on that being a surprise when you get half way through your studio time.
I'm not sure I'd want to tell the engineer about mic position unless you have some real specific info about your setup.
Tell him which driver sounds best in your 4x12 or whatever, but leave his job to him.
Once you've heard the sound certainly ask if you want it brighter, beefier, whatever.
If you have commercial reference material, try to get it to the engineer in advance of the session.
It's a waste of your time to sit and watch him listen to a blink-182 record or whatever.
I like the idea of having an appointed 'producer'. It keeps things so much simpler.
I often deal with bands where two members take me to the side and ask for opposing things behind eachothers backs.
Also, and this is pretty much impossible, but try to get everyone in the band to embrace the fact that they won't be the loudest thing on the recording.

That should save a few hours.