I suspect the key difference here is that "What are wolves like?" is asking about broad features of wolves, whereas "What kind of wolves are they?" is asking what specific sub-type of wolf they are, within the greater thing that is wolves. You're asking for a different type/level of detail or information.
"How are they like" is not valid English unless you follow it with something like, "How are they like each other," which is something completely different. I think you're looking for the difference between "What are they like" and "How are they." If you're talking about people, "what are they like" is most commonly an inquiry about their personality, while "how are they" is most commonly an inquiry about how someone is feeling. With objects, "what are they like" is most commonly either an inquiry about the properties of those objects or how they compare to some other object, while "how are they" is most commonly an inquiry about the current state of those objects.
I have a question: What is the function of "zač" in this sentence? In the dictionary it only says that it's the contraction of "za co", with an example sentence similar to the pne you gave, but since prepositions don't have a one-to-one correspondence the meaning of the word is not so clear to me...
This quite idiomatic now, the word is not used outside of this "být zač".
"Co jsi zač?" - "Who are you?" "What kind of person are you?"
Do not attempt to translate the word alone. It will not make sense.
Somewhat archaically, it is actually still used in the literal sense "za co" for the price of something:
Zač jsou ta jablka? - How much are those apples?
(meaning za co? for what?)
There some more idioms with zač, like "proč a zač", but I suggest not to worry about those.
I would say that in this type of sentences zač is not the abbreviation of za co.
If you ask Jaký/á je? Then you want to know either his/her physical appearance or his/her chatacter. It just depends on context.
Co je zač? Then you want to know her/his character.
But zač is not commonly used in spoken czech it's mostly used on literature.