well as far as heat goes you will eventually want to have a heater. dont be worried too much about cost because they last a long time. if you want cheap fish supplies go to craigslist.com
and then go to the pet section.
my bettas werent interested in flake food either
but when i got "betta bites" (you could use any food made especially for bettas) he loved them. :)
i'm no sure how long of a memory span they have but the hiding thing most likely is just because he desnt completely know you yet.
once he realizes that you are there to feed, clean, and love him he wont shy away from you. :D