I'm more than certain that Moka can drink any kind of fluid outside of plain water. As long as it's not regular water she should be fine. I'm pretty sure we've seen her drinking other kinds of beverages before.
The anime is never a good place to reference for anything R+V related btw. But I'm pretty sure you know that already
There are some lore that silver harms vampires. If I'm not mistaken the Van Helsing lore involves silver with vampires as well.
I would like to see Tsukune go against Kiria also, since he's obviously a tier or two below Miyabi. I'm fairly certain we'll see Tsukune fight his way to the top.