The Portamento can be switch on and off. The Portamento has modes: “Normal” and “Legato”. Has a Rate and Time setting and last but not least, a note from which the portamento should start before it ends up at the note that is being played. See page 20, top left section. Maybe you need to fiddle with those settings to get what you want.
You are right. The different partials just need a different “offset”. So it’s easy to assign all the modulators for another partial when you have one partial done. But That’s just achieved by copy and paste. There’s no macro way of handling it, unfortunately.
Duplicate panels. Might work. But isn’t easier for the end-user to put it all in one panel?
For the AU and Logic or reaper questions, can’t help you with that. Windows user here. There’s a mac in the house here somewhere but it’s occupied by my Gf.