The clear stand that comes in the kit? No. That's not a base, it's just a plastic piece of the kit to hold it in the air.

Not if you take photos of it before placing it in the water, just flat on a piece of blue stock would work.

Don't submit pictures with figures, it goes into armor. Submit pictures with figures, it goes in open.

Yup, unless of course you do as the video says (and what I typed above) and take the photo prior to adding those things.