Two questions:
1) Are there boat tours leaving from near Na Plavka?
2) Any decent Czech restaurants near Vaclavak to take tourists without breaking the bank?
Not sure if you'd consider it decent, but there's a couple... Titanic on Stepanska isn't horrible. My wife likes Restaurace Kyvadlo on V Jame. I'm not a fan, though. Both of those are pretty cheap Czech restaurants, not touristy, but... they are cheap.