Are there any creeks/springs, or no chance?
There are a few small creeks. They usually do not reach Rio Grande and dry out somewhere below the mountain. Most New Mexico rivers are seasonal - dry in the summer, but running in the spring...
Yes, but they are not too aggressive. I stepped over many rattles, and they did not bite. They disappear once you get over 3000 m.
Sounds like they're quite like European vipers - you just have to be careful where you step/sit. Do they go away when they sense the ground shaking under one's feet? Over here you just keep hitting the ground with a sturdy stick while walking over grassy terrain packed with vipers.
A few times I saw rattlesnakes I nearly step on them. I did not try to scare it or create some noise. They appear actually pretty harmless. I think the young ones are the most dangerous - tend to release poison, the old ones bite just dry (without releasing poison since we are too huge for them).
How big/little are the young ones, i.e. is it easy to spot them against the ground?