Hi Timchopunk,
I did not try the 3D Actor implementation, yet. Some others here might give you more information about the actual implementation, but if you take a look at the WME Demo you can already see how the 3D actors behave. I never played AITD 4 but if you mean the general Style of the first 3 games it's fairly simple.
The actors were 3D but not the rooms. So actually you just create the rooms from whatever angle you wish, make your walkable areas and implement your 3D actor. If you want the rooms all to be in different angles (top, side, diagonal view) I don't know if you can simply tell the game to change the view angle of the 3D character or if you needed to implement it in different angles. Mnemonic please help out here :-)
What do you mean with "Shoting"
Do you mean shooting with a gun?
In this case create a entity (e.g. Bullet) and have this entity move (you might also use the method "walk" for this) in the direction you are shooting. While this object is moving you can have it's position checked. If it enters an area that would mean a target hit you can trigger the hit as an event. If you can tell me clearly what you are trying to do, maybe I can give you an answer.
Another thing you have to keep in mind is, if for example a monster is to follow you through many screens. You simply have to, when loading a new screen, transfer information of the following monster while the new scene is initialized.