pbandj, Most hikers carry a water filter, and filter several places along the trail. You only need a small amount to carry and sip on the way to Trail Camp, if you drink as much as you can at each water crossing. I myself skip the filter and dip and drink, but many people are reluctant to do that.
After Trail Camp, most people carry 3 liters. The idea is to finish one by Trail Crest, and save one for the way down from the summit.
The paracord was more of a joke. People don't really carry or use it.
For training, people use all sorts of variations. Go to the gym, or just jog several times a week. Or go on long hikes in the weeks before you go. Maybe others will suggest what they do.