I suppose that ETH00 is the interface connected to the WAN router and ETH01 to the LAN switch. If so you should assign the following global values:
ETH00 Maximum bandwidth: 1Mbit/s
ETH00 Guaranteed bandwidth: 1Mbit/s
ETH01 Maximum bandwidth: 20Mbit/s
ETH01 Guaranteed bandwidth: 20Mbit/s
and how much bandwidth should i assign to the P2P class without getting aggressive P2P clients?
You should limit the outgoing P2P (ETH00) with 200Kbit/s