I'd say the 106gph should be fine. The betta will appreciate a softer flow and it will still turn your tank over 5 times every hour. I like to have my in- and outflow on opposite sides of the tank, but that's just my preference. Some put them side by side. Bettas or CPDs don't need warm water, so a heater may not be necessary. Also warmer water holds less O2 for the fish, fwiw. If you notice dead zones (I'm thinking you won't) a small power head can be put in the back out of sight. As for spin or lilly pipe types, I'll let someone else share their experiences, I don't have much on those