Yes and both "(Ty) chodzisz" and "(Wy) chodzicie" should be accepted.

I am (99%) sure what you mean, but next time please specify it ;) But this is almost certainly about the fact that "Ty spacerujesz" and "Wy spacerujecie" have been starred answers. "spacerować" is "to stroll", "to take a walk". The problem is that this sentence is shared with the "English for Polish" course, and they prefer to translate "walk" as "spacerować". However, some of their sentences also use "chodzić" as the default answer, so I believe it shouldn't be a problem if I change the answers here to "Ty chodzisz" and "Wy chodzicie".

Maybe this will help by comparing it to any other language you know? https://en.wikipedia.org/wiki/Voiceless_velar_fricative

"ch" and "h" are the same sound. I'd say that "j" in Spanish is the same.

Take a look here: https://forum.duolingo.com/comment/14133434/Is-there-a-pattern-for-conjugating-Polish-verbs