I also have Mares Quatros, love them. But they're a little bit on the expensive side for a one weeks use. I would recommend to get over to the Dive Friends retail shop on the Hato traffic circle first thing after you get here. And buy a pair of their house brand booties (CDT Caribbean Dive Trading) I think they are around $40, maybe cheaper if you get the low version. And a pair of strap fins that are within a reasonable price range. The TUSA's are pretty cheap and do the job just fine. For 100 to 120$ you will have a good set up. If you want to get around and check out all these places you will be happy you made the investment.
Yes, she can snorkel salt pier while you dive. It's easy going there, no problem. It's a good spot for Turtle too. In the shallows on the right/north side of the pier. There are several hanging out there. Stand on shore and scan the surface, you'll see them pop up for air one after the other!
One I forgot to mention in my list of good snorkel spots is Playa Frans. Nice to snorkel over and through the shallow barrier reef heading left from the fisherman's huts there. Since it's way up there it could be a good combo with either Ladania's Leap to Karpata and/or Candyland & Taylor Maid.
Snorkeling in the Washington Park....
Playa Funchi is nice. Right side, over shallow reef and along the cliff face on right hand side.
If it's calm!! Boka Bartol is a good snorkel spot as well, Stay in shallows and navigate the old barrier reef.
I could not care less about Wayaka, sure.. nice setting with small beach. But a LOT of algae, not much coral.
Slagbaai is good on right side close to the cliffs. And very nice reef at about 20-25ft a little ways to the left of the bay. (beware of current. if it's strong head to shore and swim right along shore to get back to exit)