Good question on the transfer fees, I wish I knew, but did not catch that. I will say had had zero WAX within my wallet when I created it and started out all these ventures. I have since added to my wallet to buy, but as far as I can tell the fees would come in when selling but not necessarily with the transfers... however, I do not know.
When putting up the auction on AtomicHub I went ahead and pulled that page up so you can know those fees at least:
Fee Summary
Collection Fee 5.00%
Marketplace Fee 2.00%
Tokenomics Fee 2.00%
These people must be living like damn kings off the percentages of my 14 cent sale! lol. It was surprising to see the Splinterland cards somehow fetch different values, but no doubt that occurs on secondary markets of all kinds. I have used PeakMonsters in the past but never really check it, I bet there are tons of users making tiny profits just selling cards back and forth on different markets.