A lot depends on how much detailed answer you are seeking, you asked in a High School forum, so I assume HS level.
In the case of a strong acid adding salt doesn't matter at all - it is still fully dissociated and (assuming there were no volume/concentration changes) pH doesn't change. In reality it is a bit more complicated.
You are right with 2. though, yes, presence of CN- will shift the dissociation and the pH will go up.
3. is OK as well.