your questions are really a little on the vague side. What size tank will the eels go in? Some types of fish are more burdensome on the biolaod than others....what were you considering?
most eels should be fine in that... as all eels are very big waste producers i'd only add one eel per tank unless ur tank is about +6 ft long and about 180gal..
I really want to get a snowflake or some kind of moray. I know some of the morays get really big like 5 feet or so. What do you think about having a eel and a trigger in the same tank the compatibility charts show that it is okay and some of them say use caution. I would add the most aggresive one last.
A trigger and an eel in the same tank would be a nice combo. That would be about all you could have in there though because they are both messy eaters and tough on the bio-load.