1) Do not place a comma before "that"; 2) Do not place a comma before who or which if the information provided by the relative clause is essential; 3) Place a comma before who or which if the relative clause is not necessary to know who or what the speaker means.

If both groups (clauses) are equally important, do not put a comma before "as well as".

A comma (,) before such as is required if the clause that follows is not essential to the meaning of the sentence. Do not put a comma before such as if the second clause is essential to the meaning of your sentence.