Yes,Neteller is working in Sri Lanka and it is trustable.I better recommend you to use Paypal,Moneybookers
Do not use GayPal from sri lanka, you cannot receive money so you have to use another country's paypal and therefore you will get into trouble. Try AlertPay or Liberty Reserve.
I didn't know that. It makes me interested to join them now. But not a lot people use it, that's the problem.
Neteller are of course an excellent organization. They are publicly traded and have excellent market penetration in a variety of markets and industries. In the end the best processor for your business will of course depend entirely on the nature of your business and the preferences of your customer base.