4. Can I use additional reusable earplugs for sleeping as well, or not?
Yes. They are made from silicone, so should be waterproof totally.
5. Can I use them for shooting?
That`s correct, they work fine and as the product says - NRR is 32 dB, so it is more than enough.
6. Is this ok for scuba diving
Definitely. Reusable earplugs are ok for all kinds of water activity.
7. My Amazon search was for “latex-free”. Are these really a latex-free?
The product is certified, so you can use them safely, no worries.
8. Will these for sleeping as well? Your earplugs for sleeping I ordered before are no longer available here?
These work great for bathing, I would expect them to work at that even better.