Bike sizes vary depending on the measurement technique and other factors. That's the best way to know whether you'll be able to stand over the bike comfortably. If you're doing most of your running on trails, consider a trail-running shoe. Trail runners can be more comfortable on varied terrain than a regular running shoe. The answers will get your closer to your perfect ride.
Steel makes a slightly heavier bike but absorbs road vibration better than aluminum.
Aluminum is naturally more brittle than steel. Whether that matters for you depends on how much you ride, where you ride, and how much you notice those vibrations. The random number generator. It's not just the stuff of brave new worlds and concentration camps. Eugenics has fascinated people in the United States and England for more than a hundred years and still comes up today in discussions of abortion and the Human Genome Project.