changing water

Hey there guys, hope your you and your fish are doing great :):). I am kinda new in this industry and having a betta tank myself. I was wondering what is the best way to change your betta tank water in new and old Tank (Both)? Also, the easiest way to do so. Any information will be helpful. Thanks

I feed my fish an hr to 2 hrs b4 I change the water. How long do I wait b4 I feed them again? It's a tropical tank. I do 1/4 of the water and add Quick start to my bucket as I refill, 1/2 the amount per each 2 buckets. I add Stress Coat after that to the waterfalls stream from my filter for...