Some bettas flare at anything and everything. Some get easily excited or feel threatened easily.
With your size of tank, NO TANKMATES. SOME 5 gallons can be shared with a few ghost shrimp due to their small bioload, but I would NOT put an african dwarf frog in with a betta unless you had a tank 10 gallons or larger. ADF need at LEAST 3 gallons on their own, per frog. They need room to swim and have their own territory. They can be territorial. Plus bettas often steal food from the frogs, causing the frog to starve.
If you REALLY want tank mates that badly, get a bigger tank. I'm talking 10 gallons or bigger. Even changing the water every 4 days, you still would have a large bio load and your betta would not be happy with tank mates. And the tank mates you are wanting would not be happy in that size of a tank.
Just put some more silk plants and decorations in your bettas tank and let him have it to himself. I wouldn't even divide it. Let the betta have the whole tank to himself.
Is Gorilla glue or hot glue from a hot glue gun safe for aquariums or do i have to spray something that will make the glue safe for fish? Gorilla glue is aquarium safe. It needs to cure for 48hrs after you apply it.
Can i divide a medium kritter keeper and leave a 1.5 gallon space for each betta with a heater (will try to get one in a few weeks or so)? If you want but everyone including me recommends larger.
Are large pebbles small enough for plants to grow in? Depends on the plant. Some plants need dirt with nutrients in it. Other are fine just sitting in a tank.
Is there anything i can improve in besides getting a heater? Get an adjustable heater and a thermometer.
I would use a few moss balls to assist in filtering. I would make my self a diy mini filter with high biological capacity. As someone already said, moss balls do not filter. You can have a diy filter but most people on here recommend the Azoo Palm Mignon Filter for small tanks, which is only $8.00.
You guys mean by how much cleaning? With 2 bettas in a 3gal kritter keeper you will need to do at least a 100% water change once a week and a 50% water change in the middle of the week.
I want to stock:
1 mystery snail
2-3 ghost shrimp
1-2 african dwarf frog No. You only have room for the 2 betta. Any other animals will increase the bioload and be too much.
Can i put anacharis, anubis and java fern with moss ball? Yes. These are all low maintenance plants that don't need to be planted.
Are these heaters good for bettas: (Please visit all sites) No. They do not have enough power to heat a 3gal. You should buy a 25watt adjustable. Any heater you buy should be adjustable.
How do i remove the slime that are in the corners of the tank? You do a 100% water change and rinse out the tank with hot water.
How do i add another poll for whenever I should use 2 small kritter keepers for each betta(1 in each kritter keeper with live plants, decor, 1 snail, a few shrimp, and 1 dwarf frog; is cleaned every week with a cleaning cloth, sponge for aquarium only, and aquarium scraper). Answer asap!! I hope you aren't asking us to answer faster because you are setting this up soon. You need to do a lot more research. Kritter keepers come in many sizes, I don't know which one you are talking about. Bettas need a minimum of 2.5gal. I would not buy any other animals until you know more about fishkeeping. For a small tank this cleaning schedule sounds ok, although you do not need to clean everything like that. You just need to make sure all the poop and debris in the tank are gone and that you change the correct amount of water.
Did you read the stickies in this forum about basic betta care? Read all the stickies in each section of this forum. A sticky is a thread that has been marked to permanently stay at the top of the forum section. I recommend doing a lot more research on what you want to do and google a lot of your questions. Also many of us have school and jobs so we cannot "answer asap," just when we have the time. I'm glad you are taking the time to ask questions before you buy your fish. There is some great info on this site and with everyones' help you should be able to keep some wonderfully happy and healthy fish! Good luck!