What the heck is it with firemen thinking they can climb trees. Every fireman I have ever met does tree work on the side. So you wannabe a tree man. Fine. You need spikes, a saddle, and a rope. This will put you ahead of the curve when it comes to tree-climbing firemen.
Geez, guys, he doesn't want a lecture, he wants information.
A weaver saddle is fine, regular - sliding dee - doesn't matter, whatever you get is what you'll get used to. E-bay is a good place to pick up used climbing gear. Try to get a rope without too many cuts in it. Those are the basics, you can spend as little or as much as you want on fancy gadgets. Check out the banner ad at the top of the page for Sherrill Arborist Supplies. Lots of goodies there if you want to spend a wad.
One last thing. Put 911 on speed dial and keep your cell phone handy.
Dang, I miss Rocky.