Would Traktor suit my needs better?

I think the problem here is the NS6 not Serato per se.
The NS6 is very dated and does not enable the easy use of all Serato features (like Flip, Toneplay,… or even Slicer).

If you are unsure about those Serato Features a minor investment would be to addon a reloop Neon, which enables you to use those features.

Of course Traktor has a different approach with Stems and Remix Decks. It caters more to the “preparation” crowd. As you have to have Remix Sets or Stems prepared to rock them on stage. So a lot is done prior to the gig.
Serato caters more to the “on the fly” crowd as all tools like Slicer, Flip, Sampler or TonePlay, SliceLooper etc. can be used to modify the track on the fly. However this takes a lot more practice to pull off. So the time you spare at preparation of tracks you prolly invest in training these skills, as the usage of those highend Serato tools is much more intense and needs fast reactions on stage.

So if the Traktor way is more of your thing I would rather save money and go for an S8.
If you want to try the Serato way, look into the reloop Neon to try that out.

Yes I think the Neon can compliment any controller.
I even still use it with the MCX8000 as it gives you an extra set of performance pads to work with.

That looks like strong wear on the faders. I actually would not have used the alcohol as it tends to creep into fader housings and de-grease the internals which can be not so good. You might want to remove the lube and try to spray in a little WD40 first then re-apply the lube. That could make it a little better. After spraying the WD40 leave the unit dry out for 24 hours before applying lube or anything.

Yes they could. I did not try Serato Remote but TouchOSC. However my problem was the lack of tactile feedback in a dark DJ booth, the constant glow of the iPads screen overwhelming the glow of the controller knobs and the capacitive input sometimes misfiring. So while it does work if you want to try it and maybe for you it will work, for me it did not, as it takes practice to learn Slicer and especially Flip to pull of cool things and I need to be able to do it blindfolded and fast or -> trainwreck the show.