Personally I would ask myself some critical questions.
- What is the output going to be used for?
- How isolated are the sounds? (i.e. how much bleed is there from one item to the other?)
- Do you have any life outside this project?
If the output is used to give the students a memory of what they did, I wouldn't spend the time to fix timing. You will spend DAYS fixing timing on that much material, and make them think they are better than they are. If it is used to promote the school/fundraise, etc., then fixing the timing may be worth it, but you would only want to spend the time fixing the timing on the tracks needed for that (likely half of the material you recorded if producing a normal length album, probably only one song or part of a few songs for promos.) For that matter, if this were for a promo or album I would try to record in a studio. If budget doesn't allow that, maybe try overdubbing vocals and acoustic guitars? (Even the DI output of an acoustic guitar can catch a lot of stage noise if the guitar's pickup uses a microphone...)
If the sounds aren't isolated well, you are going to run into a huge headache. For instance- if you move the drums forward a bit but don't adjust the vocal mics that have heavy drum bleed, you will cause some issues with clarity/phase.
The third question sounds tongue in cheek, but I'm really serious. If you have any life outside of this project that life will suffer for a while as you try to complete it. If you have people that are expecting everything done perfectly and quickly I would reset their expectations. You are volunteering. That doesn't mean you need to give them your sanity too.
That all said, if you still want to give it a shot, I would do the following.
1. Start with making things better at the source. If you can take a DI out from an amp it will be much cleaner sounding than a mic in front that is right next to the drums. You may have to tweak with an amp sim for tone, but the added isolation is worth it. If you're not using a drum shield find a way to get one. DI keyboards instead of micing amps as well (or take MIDI from them if you can.)
2. Think about how best to split it up. Doing one project per song might be more work than help. Are the students using the same instruments? Playing similar styles? If you can split into three projects that have similar instrumentation, for instance, instead of one per song that will help you keep the mix organized and will help you mix more efficiently.
3. When it comes time to mix, do one song first. It is likely you will be able to re-use what you did for many of the other songs by using Track Templates, FX chains, etc. At the very least, your settings for one song will be a good starting point for the others.
4. Do yourself a favor and start by setting the low and high filters on everything before you do anything else mix-wise. There can be a lot of bass/rumble in vocal mics, and way too much cymbals/snare sizzle in guitar/bass amp mics, etc. By setting your filters first you save yourself from a lot of headaches later on in the mix process. The classic filters for vinyl mastering were 47 Hz and 12kHz. You probably won't hurt anything by setting all of your filters to default to this for all instruments, then move the low filters for the bass, floor tom, and kick below 40 Hz, and the high filters on the drum overheads back above 12kHz. Your guitars and keys will probably benefit from low filters at 100 or even higher. For vocals, I would start with low filters cutting all below 100 Hz and work your way up. Cutting off the highs above 12kHz will likely help too given cymbal bleed.
5. Similar to using the filters, decide what you do/don't need from each track and remove sections you don't want. You don't need the guitar amp track during sections where the drums are playing loud and there are no guitars playing, for instance. Be careful when cutting out vocal mics, though, as these often catch so much drum bleed that it can be hard to keep the drum sound consistent when cutting out vocal tracks where the vocalists aren't singing. Automation can be your friend here- turning the vocals down a little is more subtle than cutting them out.
6. If you have a drum sample replacement plugin (Drumagog, Slate, etc) use it for the kick, snare, and toms. The likelihood is that the drum tones live are nowhere close to what you'd really like to hear, and this can really tighten up the overall tone.
7. Don't compress too much. Compression with output gain turned up can sound great on many things, but for live recordings with a lot of bleed it just raises the volume of the noise/bleed. So generally I would use limiting to tame peaks a bit, but stay away from compressors with thresholds that are too low.
As for timing.
1. Don't try to quantize things unless you are going to try and add other MIDI tracks or loops later. It's WAY too much work and can kill good vibe, too. In your case I would NOT use AudioSnap.
2. Instead, I would manually fix places where there is an instrument that is obviously off compared to others.
3. In general, if things are a little off and you want to fix them, but no single instrument is obviously off, move the drums instead of the other instruments. The reason for this is simple. It is much easier to see where the drum transients are, which makes splitting them more accurate, and aligning the drums to where the other instruments sound right is easier than the other way around.
4. When moving drums make sure you move all of them together to avoid phase issues. Clip groups can help with this. Essentially, before you start moving select all the drum clips, right click and choose to group the clips. There is an option in the Preferences that determines whether new groups are created when you split the takes. Make sure this is checked. Then, when you split the drum tracks all of them will split and move together.
5. Remember: "Done and not perfect" is better than "perfect and not done", because "perfect and not done" is neither. Figure out where you want the bar to be, but be realistic. These are live performances from students that are recorded in a less than ideal environment. They won't sound perfect.
Peace,
Tunes