Re: Spring Training Particulars
To piggyback what Doug said, usually the team the a minor leaguer is placed on is a level above where they'll start out the season. This is because so many people start out in big league camp (and to see how they do against "advance" hitting/pitching.) For example, Robert Stephenson may be on Bakersfield's team to begin camp, but will likely end up back in Dayton to start the season.
Also. as Doug said, minor league camp starts about mid March and they have camp days of just workouts and then after a few days they start playing inter-squad games and then play other near by minor league teams.
Also, a big league team calls up minor league guys for game or two that weren't invited to big league camp as insurance for a spit squad game or just an extra bat or arm in case something happens.