Everything you are asking has already been asked a million times around here. Just search it...as for your question...

Sites usually list their yields by per meter squared, usually under a 600-1000 HPS SOG type set up..Which was already mentioned somewhere in this thread.. SOG= many small female clones grown side by side to produce a sea of main colas instead of a few bushy plants...

Yield depends on experience and greenthumb ability...

Words from a rookie that has been in the game a few years already;;; START SMALL AND WORK YOUR WAY UP SLOWWWWLY. Dont worry about yields because it is too many variables.