Simple question about mesh dimensions and textures

[technoinside]

Hi there!

Although i´m not new to 3d modeling and programming this is my very first time with an 3d engine.

My first project is something similar to vr-walking (in project announcement forum).

1) Let´s suppose i´m modelling a complete house in rhinoceros or 3ds max. What´s the best scale for building the model? It´s a good idea to model in real world´s dimensions and then scale on irrlicht or before exporting?

2) And about texturing this model? Any advices about picture dimensions for getting a really good quality for this kind of visualization without loosing too much performance?

3) And last but not least, is there any tool for generating lightmaps in a complete automatized way (example: command line for loading a scene and objects, then generate lightmaps)?

Thanks in advance for any help =)