I've found that our bettas like a good flow from the filter. they'll often have a fun time swimming into the current and letting it push them back until it's too weak to push them any further. An adjustable filter is good, if you find one you like, since you can adjust the flow to suite the betta's needs - Tetra whisper filters have adjustable models even for tanks as small as 2.5g i think if you have them there. It's not necessary though as a filter made for a 5-10g would be good and make a happy betta.
dwarf puffers are very cute little fish with a lot of character (we were just looking at some today at petsmart and wishing we had another tank for them).
http://www.dwarfpuffers.com is a good site for them, especially if you decide to get some and you can talk with the other dwarf puffer owners here in the puffers forum to get a headstart on having a tank they'd love.
you can call me dave, but you must pay a toll.

every one of our bettas have air stones - it's good for the water and helps keep the surface clear. a lot of times bettas will enjoy playing in the bubbles too. if you can run the air line through a gang valve, i'd do that so that you can adjust the flow to be 'just right'.