Late to the party here, but you'll have to be a little careful on your stocking plan here. Flame angels CAN be coral nippers. Not all of them are, but IMO it's not a risk worth taking if you like corals. Also, that tank is a little small for a mandarin. TBH, the only way I'd put a mandarain in that tank would be if I saw it eating at the LFS with my own eyes.
And lastly, a Tridacna Maxima clam will require a LOT of light, at least a 4x54 watt T5 setup (with individual reflectors), or metal halide lighting.