Yes but any will do for a tube installation. The stans is great but is made for sealing the rim air tight which is great but not necessary, you only need something to protect the tube from the drilled spoke holes so any cheaper version will surfice as well.

Yes

There are still holes in the rim so you will need some form of tape on the rims to protect the tubes. You won't need 'stans tape' if you aren't doing a tubeless conversion.

Usually yes. the holes in the rim that allow the spoke nipples to be put in have sharpish edges, and the tubes have no strength of their own. You need rim tape there to stop the tube being forced down the hole.

You don't need Stan's rim tape for that though if you're using tubes, normal cloth rim tape will do.

I bought this from wiggle and it was the proper stans tape.

yes - it's the actual rim tape - hard to tell from photo

Yes it is the real thing! And do not underestimate it))))) It very strong)

I have exactly that combination and it works fine.

Yes you can actually but you'll probably have very small air leeks for sure 100%
I have already tried!)
The tape will seal only the rim not the part that connects it with the tire!!!

I think that you can use the 21mm one cos the rim is very thin! 25mm is for DH, Enduro, Street, FR, Trial, (Some) AM rims only!

Yes it will work fine! You just have to select the right width! And no you dont have to use a rim tape with it! The valve you have to tight it well so it doesn't let air out!