Answer:
What can get you there in eco style, pushed by your legs mile after mile?
Some adults still use these to count.
What object has keys that open no locks, space but no room, and you can enter but not go in?
One am I, among six others: Largest, smallest, cold, dark and two brothers
It comes from crystal and melts to a treat. Add it to your tea to make it sweet. What is it?
I am the fountain from which no one can drink. For many I am considered a necessary link. Like gold to all I am sought for, but my continued death brings wealth for all to want more.