Can i use 'Twitter search' to return tweets from a specified user?

Maybe. Twitter Search is used to search all of twitter. It will return a collection of... collection variables based on "Text to search" criteria. So if you search a specific keyword, it will return all tweets from all of twitter containing that keyword. At least that's how I understand it. What you could do though, is loop through the collection you created for "From user" and return tweet results when it's equal to the user you want. Seems tricky, gotta play around with it.