There are two options for water gates. One is to download a template from the market that has the water walls and gates in it. These gates are made of doublestacked palisaide walls.
The other option is to create water gates. This is done by putting a gate on dry land and then very carefully drawing the water up close to it.
The sound files, as far as I know, don't have a complete list. I do know that each found file is categorised by it's first letter, relating to it's campaign name. Sounds from the wallace campaign start with W, Joan with J etc. What I do is when I know the accent I want I just load up all the relating files into winamp and play them through to find the good ones. You can try E-Mailing ES and asking them for a list because they will have one. You might get lucky.
"I support Brad. It's certainly a bad idea and it would ruin the forums, but it'd be funny" - Sukkit