Nickfish,
The tank is off to a fair start. I'd certainly add some more rock as your budget permits. Your bioload is small so the filtration is adequate for now. When the fish grow or you add more, a good skimmer will be a nice investment. I don't think anything is going to die any time soon. Your eel looks fine, and there are variances in color with snowflakes, with some looking darker that others.
When I kept aggressive fish a few years back, I had a snowflake and various triggers. They are hardy fish for the most part. Watch your water quality since these guys can generate a lot of waste. If you have good circulation, any waste will be suspended long enough to be picked up by your power filter. Keep at it, add some more rock. Have you thought of a backround for the tank to hide the power cords, etc?