the main problem with feeding live to your fish is that the excess fat causes bladder problems, and can potentially introduce disease into your tank.
I switched from a community tank to an aggressive tank and i love it. i have a lunare wrasse, that is about 4 inches right now and keeps on the move. he is non aggressive towards the tankmates. i have 3 clownfish and several damsels which i use to acclimate my tanks, which works great for me.
mandarin fish are hard to keep, as you must have perfect water peramaters. plus he would never survive with your other list of tankmates as he is shy and likes to hide.
Aggressive fish are much more hardier than community fish. they have to be to eat the meats that they eat. they do put out more ammonia because of being sloppy eaters.
As a beginner I would enlist the help of people on the board to help find the best fish for you to start out with.
mandarins, butterflies, angels, some tangs. are not good fish for beginners.
hope this can be of some help for you.