Volume issues with backing/pre-recorded tracks?

This seems like a really dumb/simple issue, but here goes -- the heart of my live setup is triggering tracks from an SP404, and I'm always playing a mix of pro-mastered songs from different releases and songs I've mastered myself (badly, and these are usually much quieter). And I don't seem to be very good at adjusting relative volume on the fly, on stage.

DJs must deal with this all the time. So really I have two questions:

1) If I were to make new versions of all my tracks ahead of time and get them to the same relative level, what's the best way to do that? Just throw them all in the same session and adjust the gain of each until they're peaking at roughly the same place? Is it a bad idea to throw additional compression/limiting on them?

2) Speaking of which, is there a good way to deal with this on the fly? Like sending everything out of my stage mixer through a compression pedal on the way to the PA?

I'm sure this would be easier if I was using a laptop instead of just hardware. The only visual level indicator I have is the master channel on my (shitty Behringer) stage mixer, which admittedly I forget about and should probably use more. But the LEDs don't seem to be that accurate or sensitive (like an important change in volume might only add one more row of lights).

2. sounds like a bad idea, unless you're going for a janky sound. Compression pedals are not designed for that kind of signal.

1. depends on what your DAW set-up is, but you can basically "master" your tracks yourself with very little effort or knowhow using gain adjustment and the easily-found-cracked Waves L3 Ultramaximizer plug-in. That's what I would do, and then reload them into your sampler

Cool, that's what I figured. I never got those Waves cracks to work for me but I have equivalents, I'll try putting all the tracks in the same session and playing with limiters/maximizers/gain adjustment.

that was easy, i feel stupid for not taking the time to do it long ago.