Hi! And welcome to the forum! A few people on here might tell you to get a bigger tank, but I kept both my betta's at some point in a 1 gal, so don't worry. : )
-you SHOULD get a heater, but, in a 1 gal, it can be hard to heat the water without boiling your fish. I used a Hydor Mini Heater for a couple of years and loved it, (it's $12-$14 at petsmart,) you just need to buy a decent thermometer ($2 at petsmart,) to keep an eye on the temp. The Hydor only raises the water temp 5 or 6 degrees above room temp, so you might have to experiment with where you put your bowl. (Water should be around 76-80 degrees F.) If this won't work for you, you might be able to use a lamp, but the water will get cold at night, because leaving the light on 24/7 will make your fishie bonkers!
-In my old 1 gal, I did 100% once a week and ended up with fin rot killing my first guy, Phin. So I would suggest a 20% water change every couple of days and poss. a 100% once a week, or a 100% a couple times a week, whatever is easiest.
- I net my guy, but even though it didn't used to stress him out, it has started too, so I'm going to try cupping him. Netting is where you catch them in a net and transfer them to another spot (putting him in the small cup he came in during water changes is fine.) Whlie cupping is using a small cup and scooping him out of the water; this is supposed to be alot less stressful, and less chance of a fin getting ripped.
-Pellets are more nutritious than flakes, but either will work. You can also give them bloodworms a few times a week for variety. I do pellets and flakes on different days. And if your fish doesn't take the pellets very well, try soaking them in tank water for 30 seconds first to soften them.
-Bettas like to hide, so they love a cave/ mug/ shelter and some plants. Just make sure that everything you put in there is SMOOTH! I've been dealing with fin issues because I was too cheap to buy a silk plant from the aquarium section at petsmart, and bought a plastic one instead. If you're not sure if something will hurt your fish, run it over pantyhose; if it rips/ tears/ or runs the pantyhose, it will rip your fish's fins.
Bettas are so much fun and have alot of personality. They love to flare at reflections of themselves (just not for more than a few minutes at a time,) and i've discovered they also love chasing laser pointers. : ) Feel free to post any questions, and remember, the only dumb question is one not asked! : )