What does "peer sent transaction already received" mean? This is  my output from p2pool.

2013-07-10 16:06:29.543000 P2Pool: 17383 shares in chain (17388 verified/17388 total) Peers: 11 (5 incoming)
2013-07-10 16:06:29.544000  Local: 0H/s in last 0.0 seconds Local dead on arrival: ??? Expected time to share: ???
2013-07-10 16:06:29.544000  Shares: 0 (0 orphan, 0 dead) Stale rate: ??? Efficiency: ??? Current payout: 0.0000 BTC
2013-07-10 16:06:29.544000  Pool: 1074GH/s Stale rate: 17.1% Expected time to block: 23.7 hours


Problem - Why are there '???'s replacing all the values?

Question 1 - What does the 'Peers: 11 (5 incoming)' mean

Question 2 - What does the following line mean? It shows up a lot with different strings of numbers and letters:

2013-07-10 16:10:01.362000 Peer sent entire transaction 59900f72264267f0fbff2041ea50d9b72ba44448aa2244429e855f5372ba2bca that was already received


Thank you for your time.
The "???"s mean that P2Pool has no estimate because nobody is mining on this node. "Peer sent entire transaction ..." is printed when a little bandwidth is wasted because peers are forwarding transactions needlessly.