All water is kosher, there's no such thing as 'special kosher water'. A mikvah is simply required to have fresh running water from a natural resource.
Yes (Code of Jewish law, Yoreh Deah 201:5).
The Mikvah is the ritual cleansing of a woman after her period, the reason being that blood is considered unpure and she has just had a period of blood! This article clears up a number of misconceptions about the Mikvah http://tiny.cc/mikvah
The mikvah attendant will make sure you're 100% purely clean and assist you in immersing yourself into the water of the immersion pool.
No, no one goes to mikvah on a daily basis.
Orthodox Jews see their rabbis and immerse in the mikvah, while other Jews just eat whatever they want. Jewish answer That would be an example of something to pray and repent for on Yom Kippur (the Day of Atonement). Mikvah has nothing to do with it.
Fresh water chestnuts are fine. Canned water chestnuts require a kosher for Passover hechsher.
Yes, provided it doesn't contain and hasn't come in contact with non-kosher ingredients, hasn't been processed or packaged on equipment that's also used for processing or packaging non-kosher beverages, and doesn't go into containers previously used for non-kosher beverages.
No, frogs are not kosher. Only land animals with divided hooves and chews the cud are kosher. Only water animals with fins and scales are kosher.
The mikvah
In Over Our Heads - 2010 Mikvah was released on: USA: 29 June 2010
That depends on what it's made from. If it's known to come from a non-kosher source, then it's not kosher. But if the source material is unknown it can be presumed to be kosher.
All salt is kosher. "Kosher salt" is a particular grade of salt, with coarse crystals, that is used for making meat kosher, and is also useful in cooking. It's no more kosher than any other kind of salt.