Dzemo, that's a cool looking scene, nice work. I like the overall feel. For things not showing up in your renders the most commonly made mistakes are to use mental ray materials and try to render them in maya software which is not capable of doing it as they're more complicated and have to be calculated in mental ray itself. The second thing is to delete the connection between a material and the shading group which connects to the geometry. In this case you end up with black or green shaded geometry in the viewport and nothing shows up in your renders. When you have a lot of materials in Hypershade it's best to delete things by going edit>delete unused nodes because it saves you the potential problem of getting geometry with no shader assigned to it.

If you do get the shader up but just not the textures I can't really tell you what's wrong but the best way to find out is to run render diagnostics in the script editor. If you open the render view window and click on the icon to the far right maya should tell you why your textures don't show up. It's a good idea to run render diagnostics on any scene because you'll pick up some useful tips on how to optimize your scene and sometimes it might have problems you didn't notice.

I also really like that apache tutorial, though it is 19 hours of solid modeling Another great tutorial of similar caliber is the Ferrari, it's also done in maya 6 but the techniques remain exactly the same mental ray just got a bit speedier. Cartoon modeling is less detailed though so if you get stuck on realistic organics model the Haunted House. I'm also a fan of Jason Edwards, his work is great and he pays attention to a lot of things other people do not in modeling. His Chef Ramsay tutorial is great and it's newer so would work well if you'd struggle getting around the interface.