Thousands of years of happy reign be thine;
Rule on, my lord, until what are pebbles now
By ages united to mighty rocks shall grow
Whose venerable sides the moss doth line.
This is the English translation of Japanese anthem.
I have some questions:
1. "Whose" is used to modify pebble or rocks?
2. It should be "By ages united," or "By ages, united to"?
3. What is the subject to "shall grow"?