Answer:
Which is the oldest tree?
What goes up but never comes down?
The more you take, the more you leave behind. What are they?
I occur twice in eternity. And I'm always within sight.
When I type I tap these on the keys
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.