Welcome to the forum.
...live, band together recording...any advice on how to set that up - mic placement.
Refer to your Owner Manual, page 29.
As to mic placement: Entire books have been written on recording with microphones, so there's a learning curve, and no magic bullet.
Cliff Notes version: walk around in front of each sound source. When you hear the sound you like, put a microphone there; but don't be surprised if it takes a while, because choice of mic, placement, proximity to other mics, room acoustics, etc. are all going to impact the recorded sound. My rule of thumb: less is better than more.
...a live, band together recording, no overdubbing...How do all the players hear?
Playing "live", they'll hear just fine if everything is amped.
Alternately, you can either use the onboard headphone jack (if only one musician needs to hear); or else you'll have to figure out how to set up an outboard headphone monitoring system for those who need it and feed it from the stereo out jacks, the monitor out jacks, or both simultaneously.
Building an outboard headphone monitor (cue) system is way outside the scope of this forum.
You may be able to find what you need/get advice at one of the on-line pro music/audio stores like Sweetwater.
Also, the "Tutorial and Informational Videos For DP-32/24/32SD/24SD", the "DP-24/32(SD) Production Tips",and the "Equipment Related Tips" sticky threads (found in the shaded area on the first page of this forum) may have some ideas you can adapt to your situation.
Good audio engineers don't come cheap or work pro bono.
Look in/search the Recording 101 section of this web site (found in the "Rock and Roll" area. You'll likely find good info there on mic placement, choices, techniques, etc. There might even be something of use about headphone monitoring systems.
And you can post general recording related questions there and get input from the entire tascamforums community; and not just DP-24/32/SD portastudio owners.
