You’ll be fine.
Finale is much faster and flowier but (with a few exceptions such as trails like “Inferno” and “Cacciatore”) mostly technically easier than the stuff in Garda.
Because Garda tends to be more technically difficult (depending which trails you rode, obviously) you tend to ride stuff more slowly there.
I know Michael well (fellow Northerner) and have ridden Garda stuff with him on 3 separate visits. I’ve also been to Finale for a week last year and loved it.
There is maybe more of a case for a full face helmet in Finale because you’re likely to be hitting everything a bit faster.
I wore full-face and knee pads all the time in Finale.
In Garda I wore both open face and full-face according to what we were riding, approx equally.
No, Finale is not a step up from Garda, just different.
Yes, a proper full-face is a good idea if you want to take Finale’s tougher trails at full speed.
No, you won’t need a pressure suit for Finale.
Have fun. I’ve run out of holidays this year or I’d have been with you on the Finale trip.