I know less than nothing about sexing ducks, but on the photo host front, I use http://www.dropshots.com. I don't use them a lot as I only post photos here, but the uploads are quick, tags are easy to copy and I haven't ever noticed advertising - I'm sure it is there, but not in a way that impedes my use of the site at all.
Your duckies are very cute.. shame it sounds like there are a lot of boys though. Are you able to get another lot in this season?