I just ran the stats up to block 645576. This is a monthly breakdown but it includes all the totals for everything you asked in the last line. In the output Shielding is t->z and Deshielding is z->t with Shielded being z->z. Output of zcash metrics script · GitHub
You can also validate this yourself should you wish - I posted this previously here: Measuring Shielded Adoption
Yes, it’s still possible to do z->z on Sprout, as you can see there were 24 for example this month.
Looks like fully shielded Sapling (17191) has just passed fully shielded Sprout (16537) this month.