Thank you so much again for all the information and suggestions, very helpful! I think we're finally getting on the right track which is exciting.
We went out this weekend and bought the Marineland Eclipse 5 corner tank and have set it up and begun the fishless cycling method and started adding ammonia last night (household ammonia from Safeway, ingredients: water and ammonium hydroxide). In addition to the equipment with the Eclipse system, we bought a heater (Penn Plax Cascade Heat, 25 watt, fully submersible) and have situated it, fully submersed, a couple of inches away from the intake tube for the filter so as to distribue the heated water thoroughly. We also bought a thermometer to monitor the tank temperature, and have put it on the opposite side of the tank from the heater. This fishless cycling will be an interesting experiment!
Two more questions have come up in my mind though:
(1) I know this is silly, but I just want to be ABSOLUTELY certain: the Eclipse tank that I have has it's filter and everything installed in a hood that completely covers the top of the tank. Can this hood somehow prevent my betta from getting air from the water surface or trap some kind of exhaust from the filter's motor? Should the hood be propped open a bit to make sure he can get air? (but not so much that he could jump out) The water level in the tank is set to what the instructions suggest, leaving possibly 1/2 to 1/4 of an inch between water surface and top of tank.
(2) Are aquarium heaters safe on acrylic tanks? I've got it attached to the tank via the suction cup mounting brackets that it came with, but I just wanted to be sure that it couldn't melt or stress the sides of the tank at all with its heat.
Again, thank you so so much for any info/advice you've got to offer!