Tool Punches
What are the functions of the hook, reamer/punch tools in a Swiss Army Knife?
I have a Victorinox brand one, and I have no idea what I am supposed to use these two for.
The "hook", as you call it, is most likely the bottle-opener, used on bottles with a press-on cap (bottles with a cap that has those sharp ridges all around the bottom).
http://www.victorinox.ch/index.cfm?site=victorinox.ch&page=181&lang=E
If your pocketknife has the type of "hook" seen on this pocketknife
http://www.swissarmy.com/MultiTools/Pages/Product.aspx?category=doityourself&product=53969&
it can be used to carry twine-wrapped packages (the knife is used as a carrying handle).
The reamer/punch can be used for leather-working (poking holes in leather, so you can insert the lacing/stitching), or widening a hole in sheet metal. It can be used to make holes in almost any hard-to-work material (like rubber, sheet metal, leather, etc); I've used this type of reamer/punch for wood-working, too.