My primary question is this; If I play a land or character with the keyword "limited' in set-up can I then play a "limited" key word card of the same type; a limited land on set-up and a limited land during marshalling, during the marshalling phase? Or is set-up considered a part of the initial turn of the entire game?

King Of Forgotten Lands said:

We prefer to call them "locations".

And no, setup is not considered to be part of the first round. So you can place one Limited card during setup *and* marshal another Limited card during the Marshalling Phase of the first round.