I am not very clear about incoming and outgoing transactions fees , please help!
Actually it is quite simple:
Incoming transactions are checked to prevent trivial double-spend attempts: If a transaction consists of unconfirmed inputs it needs to have a transaction fee of at least 0.0001 BTC.
Usually you don't really have to care about this, this is all done automatically by your wallet software.
The transaction fee for payouts is calculated the same way the official bitcoin-qt client does. The txfee depends on the size of the transaction. While a session is running the payout is calculated including the estimated transaction fee. Sometimes this estimation is not exactly matching the real tx fee, because you only know the exact fee when the transaction gets created. But usually the estimate is quite close to the real fee