Hopefully the following links will help you with these answers.
a false bottom is made from egg Crate and suspends the substrate above the bottom. A drainage layer is either the use of a false bottom or the use of materials such as pea gravel or hydroballs.
The first link is an false bottom build and the next two links are some builds I did that explain the whole build.
http://www.frogforum.net/vivarium-te...se-bottom.html
http://www.frogforum.net/vivarium-te...d-journal.html
http://www.frogforum.net/vivarium-te...cal-build.html