Two of my favorite water conditioners are Prime and Stress coat. I use Prime all the time and I use the Stresscoat if my fish get a ripped fin or something.
Prime is a bit more expensive than some of the other stuff...but you use alot less prime.Prime is 2 drops per gallon which is nice.
As far as food I use new life spectrum betta formula. My fish love it.
I used to feed them aqueon pellets and bettamin flakes occasionally...Once I switched to the new life spectrum my guys want noting to do with the flakes though.
I love my aqueon mini siphon for my smaller tanks.
I also like the aqueon heaters. They keep my tanks at a nice steady temperature. I also use cascade heat heaters...They were pretty cheap heaters from pet supermarket but they work really well and hardly ever fluctuate.I have a hydor heater and I like it...but I have noticed it does fluctuate temperature quite a bit..Usually never goes higher..but it does it colder 2 degrees or so before it turns on again...Not really sure it was worth the 40 dollars I paid for it locally..