The first file is the GTK libraries needed to run the app. The second is the gimp program itself.
The third is a lzw compression program. Since some handsomehunk has a patent on it they cant legally supply it with the program.
Layering is very good in gimp, just right click on the image and go to layers and channels.
Online help should be huge, I normally just play around till I figure it out (remember its all about the right mouse button), but open source programs like gimp have huge databases of faqs and people helping each other out. The best thing to do is type your question into google like so
layering gimp
or
layers gimp
and if that fails you can look through the official documentation here.
http://www.gimp.org/docs.htmlI always seem to find my answers with google though.
GOod luck!
