Dual collapsible "trekking" poles. Too many miles, too many falls. They do help with sketchy terrain, save some strain on the knees, and come in handy for various other uses. A custom hiking staff can be a thing of beauty, but is hard to stow when not in use on the trail.
Exactly.
I have Black Diamond Alpine trek poles with cork. They have the new flick type lock rather than twisting to seat. They hold much better. The cork is nice b/c hands get sweaty in desert summers and the cork sucks it right up. They weigh a pound and collapse well.
Make a big difference. I think they help hold my pace. They take a lot of weight off your upper body.
Regardless of type, I went with some novices to the Grand Canyon last year and in the gift shop I strongly recommended they buy the wood hiking stick they sold for $9. half came up after we were done, saying they would not have made the rim-river-rim trek without it.