Hi and welcome to the community 
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I think everybody here has his own concept about code design. I personally gained a few ideas through watching others’ projects, of which many are open source, but also watching common practices in unity3d, ogre3d, flash and a few others. I think a special Panda3D rule for design is: keep it simple. That’s why Panda offers many things as global variables in Python, I think. You don’t have to stick to that, of course.
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There are two books on Panda that were published by Packt Publishing. Also we have a pretty good manual and a few demos and code snippets on the forums. The latter is best resource for any feature you want. If you search for “my game fast” you’ll also find a very neat step-by-step tutorial.
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For modelling Blender, for environments the same and textures are done in Gimp or Photoshop. For both programs there are add-ons that help you make normal-maps out of bumpmaps. If you need procedural textures, it’s best to bake them in your modelling program and export as simple image.
Many third-party programs offer automatic generation of specular maps or gloss maps etc. The good thing is that all textures are pretty unbound from the game engine. You can create your maps with whatever you want and they’ll work in any game engine. -
Unwrapping UV maps is a topic for its own. Best is to search for that. There are also many video tutorials about this. For realistic models you’ll need photographic resources. cgtextures.com is the best site I know that has huge amounts of good photo textures. Other than that there are hundred, of which some are commercial. In worst case, get a cam and make photos yourself
. This will also help you get an eye on materials in general. -
Mythology always has been a good resource for fantasy and middleage settled games. And I’m not only speaking about greek and roman, but also about egyptian, middle-african, mesopotamian, asian and whatnot. For other genres you have to simply dive into books and papers about the topic.
A) Beside Blender 2.4x with chicken you can also use Blender 2.5 and 2.6 with the new exporter you can find on the forums. It’s called “yet another blender egg exporter” 
Make sure you set up your textures relative to the egg files and the textures need to be where the paths in the egg are pointing to. You can simply open the egg file with a text editor and search for the texture path. It should be somewhere on the top of the file.