Ahh, ok I see, primarily for field recording of multiple input sources to discrete tracks - this means that automation is not going to be an option.
Automation will let you adjust things like gain, and effects, but this is usually done in post.
if there is a noise-gate built-in with the R24, you could put that effect first in the chain (for each handheld mic track), and for a second effect, then use a limiter to prevent volume spikes and clipping and set the threshold of the limiter to -3db, which will quiet the peaks but still allow headroom for normalization in post.
I am assuming your are going to record to the internal microSD card in the field, and then do some cleanup in post on the computer? Correct me if I am wrong.
This actually becomes easier if you are going to use the computer, because of that automation I spoke of.
Most decent DAW software will let you set automation curves, and for the discrete tracks where the handheld mics are used, you can set the automation to basically null the gain of each track where there is undesireable handling noise, and then 100ms before the speaking or singing is to resume, your automation curve can have the gain back to -3 db or 0 db again for normal levels.
Once you set the automation curves for each track, when you mixdown to stereo, it's like a magic robot was riding the faders to control the levels, and your exported track will have this all done for you.
Also, on the computer, if you use a limiter or normalization to -3db on the 'master output', your volume will be even all across the runtime of the exported audio file, regardless of any spikes or peaks, and this will sound MUCH better than without.
Is this audio going to be married with video footage later on?
Have you done any of this before, like am I preaching to the choir, or is this all too techie for you right now?
Please let me know and I will do my best to help further.