New Beta fish owner

I was told that beta fish do not like bright lights or a lot of
movement in the water. They also don't like cold water being natives
of Thailand. In looking into heaters apparently you need to have a
water filter if you have a heater. The water can't be stagnant. So how
can I heat the water to a comfortable 70degrees and not upset our fish
with the motion of the filter? How much motion is bad? Is the amount
by a filter acceptable for Beta's?