Hello and welcome to the frog forum!

A false bottom is not necessary unless you have a water feature, LECA will be fine although the Leca like substance that Joshs frogs has is called false bottom.

Correct, the plants will need a light that is between 6500-6700 K.

1. If you don't use a water feature, the false bottom is just a layer of porous material at the bottom separated from the substrate with substrate barrier

2. Yes, excess isopods and springtails are actually very good for the tank. Remember to dust their food too

3. I have a layer of leca/false bottom at the bottom of my tank and there has never been an odor. I think that using coco fiber instead of ABG may cause odor, so make sure ABG mix is your substrate.

4. Not sure about this one, sorry

5. 3 frogs maximum, no more than that

6. Mixing species is a no-no in the frog world. Stick to one species

7. ABG mix

8. Spray foam is used to make the backgrounds you saw. I know that one of our mods posted a guide, i will try to find it for you

Edit: nvm, Amy's got you covered with that link