Irrlicht Engine

If I wanted to animate a tank for a RTS game, and I wanted the turret to be able to rotate based on an AI decision, should I have the tank, including the turret, all as one mesh, or a mesh for the turret and a seperate mesh for the rest of the tank?

How do I effeciently manage different scenes in a game? What I mean is, how do I switch between, say, a menu screen and different levels of a game?

On a side note, what 3d model format would you recommend for animation? I was thinking .X. Am I right?

I see to be having trouble with some RTS camera code I got from one of the Irrlcht forums. I understand the error, but not why I'm getting it. I'm using Dev C++ with Irrlich 1-3.

Here are my errors:

'pCamera' undeclared (first use this function)
'pDriver' undeclared (first use this function ...

What about water effects, like splashing? Is that possible with Irrlcht?

Awesome

Does Irrlicht have built in support for reflections (specifically, water)? If so, could someone point me to a tutorial or somewhere in the API? If not, what would I need to do to incorporate it?

I get this error when I try and compile my source code for Tutorial 1 on this website. Does anyone know why? I have already let my compiler know where to find \include and \lib.