Try the Scouting On Stamps Society International (SOSSI) website
www.sossi.org (i think). I have not done a standardized workshop, but I did meet with a troop several times before their troop meetings to check off requirements, answer questions, & provide philatelic materials. You are right about there being a lot of areas to cover, it would take all day. I suggest working with a local stamp club and tie the workshop to a stamp show. I enjoyed taking the scouts around to each dealer at my clubs annual bourse and explaining what they sold, it really opened their eyes to the magnitude of our hobby.
I give each scout a requirement worksheet and suggest they get the most recent merit badge handbook. I also made up a reference page with dozens of helpful websites and resources for stamps.
My first presentation was around an hour long and I had a couple tables full of catalogs, stamps, albums, covers, philatelic tools, etc. for the scouts to look at. Very hands on. I just explained how I started collecting & why I enjoy it. I find topical collecting gets the best response.
Also, go to the APS site
www.stamps.org and check out their free album downloads, beginning collecting area, and their youth club program.