Maroon clownfish & BTA are natural symbiots in nature. You won't necessarily be able to count on the clownfish feeding the anemone. I have a spawning pair of Maroons residing in a GBTA & it's clone and they generally don't provide food for the nem. I feed the nems a chunk of silverside once a week or so using one of those forcep tools, a few bucks at the LFS & worthwhile investment. That way I don't need to stick my arm too far into the water.
Maroons tend to be one of the more agressive clownfish species, but I've found my pair to be relatively calm, rarely attacking my hand when I'm in the display messing around. YMMV, you never know how each fish's personality will develop, it's a bit of a roll of the dice. Some clownfish of various species are known to draw the blood of their keepers whenever they try to stick their hand into the tank.
I have no experience with Puffers, Eels as tankmates, but have found that once the Maroons are settled into their anemone & have established their territory, the other fish tend to respect that & there are few conflicts. Tankmates for my Maroons include Yellow Tang, Singapore Angelfish, yellowtail Damsel & a couple of Mandarin Dragonets. It should get sorted out either way in the first week or so, after that it's all gravy. Could be casualties in that first week though, no guarantees until you drop the critter in there.
