How high does this tank sit in relation to the sump? If your sump is sitting on the ground, how many feet is this tank off the ground? That will help determine how powerful of return pump you will need.
There are a few powerheads that are more safe for anemones. You can buy an attachment to Hagen powerheads that would work pretty good. Here is a link to one of their powerheads:
http://www.hagen.com/canada/english/...01005650010101
And here is the attachment I was refering to:
http://www.hagen.com/canada/english/...01005750010101
You would just need to make sure you clean the filter regularly or it will cause you problems.
I know Blue World in Edmonton carries a more rare type of occelaris clownfish from a local breeder, that aren't that expensive, but that is quite the trip to make for one pair of clownfish.