Right click on the photo you want to post here, then copy the address. Then in your post here, click on the little photo icon (yellow) and paste in the address. At photobucket there is also the option to mouseover the thumbnail sized photo and a menu will appear, you can select the URL including the IMG tags and just paste that here (whichever is easiest for you).
Here are your photos
Personally, I'd get rid of the nudibranch. Most nudibranches that look similar to corals are predatory for that coral and are designed that way to blend in while they're killing it. I'd vote yours is likely a softy eating coral and likely hitchhiked in with it. Have you noticed any of your corals looking eaten or not as healthy looking as when you got them?
The second critter is a bristleworm. They're mostly scavengers but sometimes are identified as predatory when they get large. I'd classify yours as large, you may want to remove it...or not. Thats up to you