In my opinion, none of the above sentences are correct.
Like can be a preposition, and is used before nouns and pronouns to talk about similarity. For example:
He ran like the wind.
or
A person like you knows that..."
As, on the contrary, is a conjunction. It is used before a clause and before an expression beginning with a preposition. For example:
Nobody knows her as I do.
or
In 1939, as in 1914, everybody seemed to want war.
It is true, however, that in informal English, like is frequently used as a conjunction instead of as, so the first sentence "Do like we do." could be heard.
The third sentence is wrong because you are making a comparison and in this case as is the only one you can use. If on the contrary the concept which you want to convey is that the girl is tall and that your sister is tall too, then like is perfectly fine, but you need a comma to separate it from the first part of the sentence (that is, "She's tall, like your sister.").
Finally, you normally also use as when talking about the function or the role of something. For example:
He works as a waiter.
or
Don't use that knife as a screwdriver.
Disclaimer: The grammar explanations and most of the examples are taken from Swan's "Practical English Usage".
In English you always use/say are after a plural subject.
In this case the subject is my shoes and it can be replaced by they instead of it. So with a plural subject, are conjugation is used.
See ECEnglish.com: Is or Are?
Best Answer
As @BillJ said, "which" is used for an item in a distinct set (it is selective) and "what" is used for items not in distinct sets (it is non-selective), including where those items haven't yet been identified.
This difference is meaning is clear from the dictionary definitions (from Oxford Dictionaries):
Both of the sentences in your question could be correct, depending on the context.
You would use "what" if you (and the person/people you're talking to) don't yet know what the problems are. Perhaps you and the person have just started a new project, and you're brainstorming for issues that might arise in the course of that project.
You would use "which" if the problems are already known, and you want to know which of those require addressing (and, by omission, which problems do not require addressing).