New Betta and so much conflicting information...any help?

So I am new to Betta's (what an awesome fish...love him already!!!) and have been reading both online and in a book that I borrowed from the library about the best way to care for it but there is so much conflicting information. Some say to feed him three times a day, others once a day (small amounts that can be consumed in 3-5 minutes). Some say that I should have a filter in the tank with a very gentle flow, others say that the filter is bad. Also, what about changing the water? Some say every three days, others every week? So far I have had him for a week, Ive been feeding him every night just a small amount and he eats everything. I have him in a two gallon tank but its only filled half way until I work out if I should put the filter in (its adjustable to a very gentle flow) and Ive not changed the water, though I am planning to tomorrow and have a gallon of water in a jug that has been treated and sitting for a day now. So...any help with people who have sucessful experience with Bettas...THANKS!!!!