You might want to check this website. That list is updated regularly and you will notice that it also contains episodes which have yet to be aired. This is especially useful if you're following the series but only want to watch the canon episodes.
45% of filler episodes is a bit exaggerated. It's actually about 20%, although some canon episodes of Boruto do ...
Most of them. If it's not manga canon then it's filler. They should of just waited to release Boruto. I think there are less then 20 cannon episodes. All of the filler is why so many people didn't like Naruto Shippuden. Boruto has literally taken the worst aspects of the Naruto Shippuden anime.
Yes he can, in the manga 16- Vessel.. Boruto is having a match against Naruto and uses water release- billowing wave and mixes it with lightning style. The wiki probably just updates stuff according to the manga as well. Although he might just not use water style as much as wind or lightning.