Hi and welcome to this forum

Yes and no,

Linked channels on the console will have two faders (to keep the 1:1 relation with the channels and the scribble strips) but they will move in unison, even if you move only one.

In UC however the two faders will change into one. And on the user layer on the console you can 'cheat' by assigning only one of the two faders to it, knowing that by moving that fader the other one will move too.

Thank you.

Sad news, I thought on SL32sx it can be done the same way as on Behringer Wing or Midas.

Does the StudioLive 32 console have a multi-band compressor or dynamic EQ in the Fat channel?

Have a look here

The answer to all your questions is always No, so it seems that the Series III mixers are not meeting your expectations at all. They will NEVER have the features you are looking for because the technical design does not allow "additional" features. I use the words of a PreSonus representative:

"Series 3 DSP is fixed. Multiband, Dynamic EQs, etc, are all out of scope for this product. De-Esser could be added, but it would have to consume the Comp/EQ blocks. DSP changes are the hardest and most expensive. Currently, there is just a limitation on what you can do. All of this we are aware of, going into the next mixer generation jump."

And a quote from another representative: "We are not releasing new mixers."