I omitted an important point in the previous post which I should include before discussing installation of LuaTeX. I would like to briefly mention something called the TeX Directory Structure (TDS). Quoting from the TDS web page:

TeX is a powerful, flexible typesetting system used by many people around the world. It is extremely portable and runs on virtually all operating systems. One unfortunate side effect of TeX’s flexibility, however, is that there has been no single “right” way to install it. This has resulted in many sites having different installed arrangements.

In short, the TDS is a standard for organising a collection of TeX (i.e., and LuaTeX) files. Of course, with LuaTeX there is nothing stopping you from adopting a different directory structure but if your experiments with LuaTeX evolve into an installation which will need managing, it is certainly worth knowing about the TDS and following its recommendations.

For the purposes of these experiments and tutorials I may deviate from the TDS recommendations, but at least you know that the TDS exists, should you wish to adopt it.

Update: an interesting paper
By Michael J Downes: Managing Multiple TDS Trees.

Update: PDF version of TDS documents
Downloadable from http://tug.org/tds/