+1. I had a wave nouveau/curly perm for about three years before my final relaxer, so it was during high school for me. If I recall correctly, it's a double process--there's a "relaxer" phase which opens cuticles/break bonds/straightens hair, and then
a conditioning/setting phase where you have the hair shaped into curls. Afterward you'd neutralize as you do with a relaxer...but the chemical used to change the hair composition is not the same as that in a relaxer, so I wouldn't recommend overlapping relaxers and wave nouveau.
The pro for me was that maintenance was the easiest ever. Easier for me than a relaxer, easier than my natural hair now. I think only braid extensions are easier for me. My hair also initially retained growth more than it did during my relaxed years prior to the wave nouveau years. But my hair eventually stopped liking the process and started breaking, plus I personally didn't find the style very versatile (but maybe this was just me...I was highly style-challenged back then. still am a little).
I got processed every two to four months when I had a curly perm. I did the same when I was relaxed.
If you mean a texturizer/mild relaxer, you would apply similarly to how you would apply a relaxer. If you have virgin hair you put into into the entire hair for a few minutes before washing out, then subsequent processes you apply only to the roots. I think you would also apply as much as you would a relaxer, for some people it's six weeks, for others it's more like three months or more. I think this mainly works if you actually have some curl pattern to your hair already. I don't really, and when I texlaxed/purposely underprocessed my hair, I had hair that looks similar to my stretched natural hair, a sort of frizzy poof consisting of tiny waves. I also have a cousin who got a texturizer (same curl pattern) and his hair honestly just looked like it grew (less shrinkage). I think maybe he left it in for a minute, hence the lack of an appearance of a change in pattern. I'm not sure how to describe it, and I don't have any good pics. If you look up "wave nouveau" on google, my hair pretty much looked like the other ladies wearing it, but my texlaxed hair didn't look like the pics on google. It looked more like hair that was trying and failing to be straight.
Sorry for the novel btw. I hope I helped even a tiny bit?