Meraviglia Aurea questions

[Mom2B&Z]

We sail on Meraviglia on March 10 in an Aurea grand suite with whirlpool, two adults and a 16 year old (Z).  We have sailed once before on MSC, but didn’t fully take advantage of the Aurea perks. 
I have questions:

1.  Our cruise ticket clearly shows we have access to the thermal area. While it says access is for adults only, other cruise critic posts say that 16 year olds can use the thermal area with a signed waiver. Does anyone have experience with this?  Do we need to reserve the thermal area?

2. Our cruise ticket also shows Balinese massages available up to 2 days prior to embarkation, but I can’t figure out how to book this. Last time we booked the massages on board. I’ve tried signing in to my MSC account and adding to my basket, but it shows the usual cost. 
3. Similarly, it shows a specialty restaurant package available up to 2 days before embarkation but no instructions for how to book it. 
 

The two adults in the cabin are both diamond status if this makes a difference. 
Help and suggestions appreciated!