TO AXER;RODRI;ROTA; and ARU

I present these simple riddles:

"
  1. At night they come without being fetched,
And by day they are lost without being stolen."
  2. "I never was, am always to be,
No one ever saw me, nor ever will
And yet I am the confidence of all
To live and breathe on this terrestrial ball."*
  3. "The beginning of eternity
The end of time and space
The beginning of every end,
And the end of every place."
  4. What lives on its own substance and dies when it devours itself?
  5. A farmer combined 2 compost heaps with 3 others. How many compost heaps does he have?