10k DOGE for a pizza? It's like 10k BTC for a pizza. But now if you can get 10k BTC you will be rich.

Original (original bitcoin client) wallet.dat contains:
- keypairs (private and public keys)
- transactions
- key pool (used for faster address generation)
- preferences

If you want to backup your wallet:
- make an password protected archive file
- add the wallet.dat
- upload to cloud storages
- make the file private (if the storage is public)

If you want to see the mining profitability you can see at http://www.coinchoose.com/. As I read your message you mine with GPU whitch is good for SHA-256 mining ,but not really good for scrypt mining for scrypt the CPU is best.

Merry christmas and have a good year.