Well, updating it gives you a LOT of new features but if you don’t need them then that’s absolutely fine, it’s not necessary.
I’m not sure what it is exactly you’re trying to achieve to be honest. For instance, it might be that my understanding of western theory is fuzzy (it is most of the time!) so I’m not sure why you’d need to choose a key in order to choose a chord. Can you please explain why you’d need to set a key?
Other than that, yes, you use the Root input to choose a Root in a V/Oct fashion, and then have the Chord input to use CV to select a chord type (Maj, Minor, etc, etc). You can modify the list of chord types so that it only contains chord types you want, or, you can have ALL the available chord types in there. You’ll need to send it a Gate at the Gate input to fire the chord. So two voltages (V/Oct, and chord type selection) and one gate.
No need to do any real menu diving. You can set it once, save it, and from then on you can use CV to change Root notes and chord types and never bother with the menus again. The rest of the stuff it can do, you don’t even need to bother with if you don’t want to! So, in a way, it can be set and forget. Like a CV controlled library of chords.
Other controls, like inversion, expansion, holding the chord for arpeggiation, arp type, are all accessible via the front panel. No menus needed.
That being said, I’m more than happy to explain (in steps) any process you want to do in particular, if that helps.
Generally speaking the module isn’t that complicated, but I can fully understand why it might be daunting at first. It can do a lot of things! (with the latest firmware you can even make your own chord types, or program your own arpeggiation patterns)