Besides the cosmetic and interior differences between a Verada and Magna, can someone mention the more important ones?

For example, someone mentioned that a Verada has more sound insulation, is this true?

And more importantly, is the suspension the same?

Thanks

yes they have more insulation.yes the suspension is the same.

Although all the suspension parts are the same and interchangable, the vrx and sport magna's have firmer suspension, possibly a touch lower IIRC, and this suspension is repeated in the verada GTV spec.
There is a couple of VRX Limited Editions released with Koni's But they all would, more than likely, need to changed by now, so you can choose how firm/soft you want it, unless its already been replaced.
Later on, the sport variants were fitted with rear sway bay, and even later fitted as standard equipment on all TL/KL/TW/KW's.

Would a rear swaybar from a sports model fit a KH or would lower control arms be needed too?

To put a factory swaybar on you need to change the whole rear crossmember because the swaybar mounts are on the crossmember.You can get a whiteline rear sway that will fit on the std crossmember.