You can stay on v0.9.13.15 but are encouraged to update to 0.10.14.1.
You can keep your addresses by dumping the privkey of each address from the old wallet and importing it into the new wallet.
After importing the addresses that way you'll need to rescan the blockchain to get the correct display for your balance.
This works but the imported address wont be part of new backups correct? and it wont be in the wallet if you regenerate from seed yes?
Ive got some vanity adress that i quite like, would like to keep them without needed special attention to them after upgrading.