Responses
No he could not. He only learned water magic in chapter 44 because of the holy water. Originally his element is fire magic so... He was only able to use it now.
Is it? I don't remember. To many stuff going on (≧∀≦)
I wasn't that sure myself so I reread a bit where they drank the holy water, so trust me, that's where he gained the power to control water.
Thanks
Ch. 47, he could have done that spell back in chapter 38 to get out ╮(￣▽￣)╭