DEFINITLY use a bag that is designed for air travel - not just one of those single-layer jobbies. I always have had my bindings mounted. Wrap your boots in a base layer to keep them from scratching the board, and them put them in the bag next to your bindings to give them some protection. I also stuff my socks etc into/around the bindings to give them a little extra padding. Basically, when I fly with my board, all my snow gear including jacket and pants is in one bag - maybe not the smartest but it has always worked out for me. I have never been over 50lb, but if you are it will be around $40.
No locks, just be sure and be at the oversize baggage area when they deliver it and you won't run any risk.