Six transaction confirmations are the recommended value for transaction finality on the Bitcoin blockchain and thus its recommended to set the value at 6 confirmations for Bitcoin SONs. (reference: https://web.archive.org/web/20210218094358/http://bitcoins.net/guides/bitcoin-confirmations)
Funds equivalent of 200 PPY is set aside and its distributed among SONs proportional to their performance. This value can be changed by the committee.
No, when you are connected to SONs network as a seed or a SON itself, you won't be doing any PoW mining. SONs just listens on the Bitcoin network for any incoming transfers to Peerplays BTC addresses.