some observations I made with my pairs:
#1 I love my Kent Sea Squirt tool for target feeding. I used to just put some on the rocks and it would float away. I now aim it at a red Blasto I got from Firewater. The mandarins come to the Blasto to dine and the Blasto always gets the left overs. It's win-win and the stuff doesn't float away.
For the other fish I just squirt the food into the water column so they can chase it.

#2 I had a pair of male/female spotted similar in size and for them the arguing continued. Sometimes they wanted to be together and spawn and sometimes they fought. Kind of an on again off again thing.

#3 Because of the occasional fighting I was really worried about my last pairing of the big male with a tiny female but it actually worked out perfect. No fighting at all. Ever. So sweet. Always together, spawing in the evening and no fighting ever. Big male with small female is ideal IMO.

#4 I was hoping I could make a trio work of 1 large male with 2 tiny females and that didn't work. As fiercly as males fight each other, the females can be just as aggressive towards each other. The male would have been happy with two girls but the girls didn't agree so I would say avoid any same sex pairing: female/female or male/male

#5 Never rely on just pods to feed your fish