Just got some Apisto. Cacatuoides

If the fish are happy, healthy,the water paraments are good, and they are mature enough to spawn. They might. Although, 10gal is kinda small, thats maybe why one of your fish got killed. Not enough room. Good Luck

Congrats, be very sure you have a male and female. Many petstores only have males, just do a quick search on google and you'll find pictures of both.

Water temp I'd keep 80ish, and keep it clean, a couple 50% changes each week, high protein foods. Lots of brineshrimp, bloodworms, and the like to condition them. Then just give them sometime.

A few more things...
Make sure you have caves in your tank. The male will most likely claim the caves, and when the female is ready to spawn she will turn bright yellow. That type of apisto is pretty easy to breed.

actually with Cacts. its the females that pick their own territory, not the male. Caves will work, but they will spawn on a lot of things. Cacts. are generally harem breeders, meaning one male will tend to several females and is allowed to pass through their territories, the females however will not allow other females to pass into their territories.

For cacts the 10gal will be fine, rams it was a little small, obviously you didn't have a well bonded pair which is what caused the issue. For a strong pair bond a 10gal is fine for rams.