Those are beautiful fish. I have semi-see-through dividers in all of my betta tanks, and my betta's still flare at each other from time to time. Although they flare more at their own reflection.
I don't know about trusting that mini-heater from wally world though. It doesn't have a temp control. My sis had one and it stopped working about a week after she got it. I would get the 25 watt heater, then just keep a very VERY close eye on the temp.
I would agree with wuv, itty, and BKK about the pic. (Why then did 55 already post it for nomination?)
HTH & Good Luck,
Tiff