Filtered water. Drinking filtered water is not a bad idea as most tap water contains teeth-strengthening fluoride. Natural spring water with minerals drinking directly might be ok, but not necessarily healthier. Bottled water, however, is controversial as most water bottles are unfortunately not recycled, resulting in billions of water bottles clogging landfills each year, which cannot be easily decomposed.
Probably not. The scientific information, as far as I know, does not answer your question. The minerals in spring water are probably helpful for you and the water filtered to pull out impurities is probably also helpful. I think that in general drinking water as opposed to other liquids is healthy.
No difference. Mineral water from a spring is as good as bottled water. City water is much more controlled and hygienic than bottled water.