So there is no difference in gender when saying 'you are'? That is, it doesn't change if you're speaking to a man or a woman.
Yes. "Are you a man or a woman?" ( for example if you input some form ) is translated as "Jsi muž nebo žena?"
BUT if you want to say "You are tall." then the sentences are not same. "Ty jsi vysoký." (if you talk to a man) "Ty jsi vysoká." (if you talk to a woman.)
Does Czech not/have require "a" like Russian?
Could someone explain how articles in Czech are used?
Neither Czech nor Russian has articles.
Czech uses demonstrative pronouns (ten, ta, to) much more than Russian does. Russian (Ty žena.) certainly does not require any pronoun or article here.
why is "are you a woman" wrong here (of course of the missing questionmark, but ispoken language?)
I do not understand you.
the recommendation for "ty jsi" says "you are" and "are you", when does it mean "are you...?"
In questions and wherever English uses this word order. It is really about English grammar, not Czech.
Doesn't Czech use the instrumental case for the verb to be as Polish does? This is so much easier :D
Much less then Polish, but does. There is a subtle difference and they are preferred in different kontext.
I don't see the difference between "you are a woman" and "are you a woman?" In Czech. Maybe I'm missing something, but how can I understand when does it a question and when it doesn't?
You understand it from the intonation. Note that "You are a woman?" can be a question as well.
I'm confused about when you use "ty" in the statement, and when you just use "jsi".
Ty is used when the ponoun is stressed, it is optional.