Yeah just checked on skrill. There are no fees to withdrawal from poker sites. However, as I suspected I get kind of hosed on the exchange rate. When I withdrew from Betsafe in € to skrill in $ I got a 1€=$1.105 and at the time the open market was trading at €1=$1.15. Hence the reason to want to keep some of my bankroll in $ and some in €.
I have yet to do a withdrawal from NT, but I think they operate the same and may even be affiliated somehow, so I would expect there to be no fees when I withdrawal from them.
The fee I paid to transfer from Skrill to NT was 3% on NT's side. I paid some merchants for some poker tools out of skrill and looked like the fee for those was around 2%. I also know both of them have fees to withdrawal to a bank account, but I believe it is less than the 3% to do service to service or service to merchant. Just looked around both sites and actually can't find a list of the fees, but would imagine when you sign up they should have something somewhere.
Main thing is, normally you can only have 1 account associated with an email address and maybe even with a physical address and it can only be in 1 currency. Which is why I opened accounts in both. There is a site called Ecopayz that you have one account and can have up to 3 currencies that you can chose. So you could do £, €, and $. I live in Costa Rica and they will even let me do Costa Rican colones. They also have cards for the 3 main currencies. The challenge is, most poker sites don't accept them yet, but was told they are working on that. So probably not worth using them at the moment, but maybe in the future that would be the best E-wallet to go with.
Best of Luck