Hiya! I have to agree with hedgehog, the betta tank is your best bet. I don't have any extra aeration in my tank with my cories - if you have a power filter, it will aerate the water fine. Plants aren't as much a concern but you WILL want a cave for them to hide in, even a coffee cup or a clean flower pot on its side. Tip: you can get terra cotta flower pots at craft stores like Jo-Ann's and Michael's for cheap. Just rinse in warm water and plop in.
Your betta will most likely ignore the cories because they will ignore him. Your biggest problem could be keeping him from eating their food. I've been told to feed the cories first thing in the morning and when you turn the lights off at night. Although they are omnivorous, a diet leaning more toward carnivore is best. I feed mine shrimp pellets and Hikari Sinking wafers. My cories get their vegetable foods by leftovers from my platies but you'll want to give yours a small algae wafer maybe once a week.
Hedgehog is right, they will spawn (usually brought on by a temperature change) but if you don't want baby cories, just let everyone eat the eggs. Easy as that.
Since they root around in the gravel a lot, be sure to do lots of gravel vacuumings to keep it clean. That way their mouths and barbels (the whiskers) won't get injured or infected.
Other than that, they're wonderful little fish and pretty easy to take care of. I really love mine. Have fun with Rin and Yasu!