What was the answer to your question? I was just searching the forum and found you had the same queries as me.
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Yes, you can send to a paper wallet address as many times as you want. All the transactions are saved to the network, and once a client is created and the private key is imported, all the coins will be accessible that were sent to that address.
The "keypool" and "outdated backup" questions are referring to the behavior of a particular wallet (Bitcoin-Qt).