RE: Dynamics additional environment cost
Hi
For the first one, did you opt for any special plan? If not, it will be chargeable. But I will still suggest to ask your Technical Account Manager & consult.
With any plan you should be able to create 2 sandbox & 1 Production instance. Then you can add sandbox & production instances will additional licenses & costs
Storage capacity is limited and you would have to buy that separately from Microsoft as per need. You will start getting notification/alert as soon as you use 80% of total capacity but since storage is elastic, you can continue use & buy storage in the meantime.
For capacity, please use this link - admin.powerplatform.microsoft.com/.../capacity
this should provide you your CRM tenant usage
I have a series of blog written on storage on this admin portal - thattechiegirlroma.wordpress.com/.../
You can refer here if you wish.
Buying licenses & storage are two different things.
Hope this helps.
Regards
Roma