I'm trying to wrap my head around how polarizers work out of curiosity and I have a few questions.

1. Let's say I have a polarizer whose bars are vertical. I see some sources which claim that it lets only vertical waves to pass through because vertical waves get through the small slits. Some sources contradict this though, as claim they're actually the ones getting absorbed by the bars and don't make it through. Which theory is correct?
2. Given an unpolarized wave composed out of many polarized electric fields. I kind of "can" decompose them to parallel and perpendicular to the bars, and I "can" claim the components parallel get through (that is assuming the first option in 1 is correct!). Is this wrong simply because the decomposition isn't a valid move here? After all the waves with a perpendicular component physically shouldn't get through.
3. Why does nobody talk about the magnetic fields in relation to polarization? Is this because only the electric field is related to vision? Even so, does the polarizer affect the magnetic fields?
4. Is there a simple reason that can help one can understand why reflective surfaces (like water or ice) polarize light? and how do you determine the direction of propagation of the electric field after polarization?

Thanks in advance.