Re: Spring Training Particulars
Big League spring training is separate from minor league spring training. Big league spring training starts in a week. The minor league portion doesn't usually start until March.
Guys on the 40 man roster are automatically in big league spring training. They remain there until they are optioned to the minor leagues.
I can't tell you how it is decided on which minor leaguers get to play with the big league guys when it comes to non-40-man and non-roster invitees go.
With the minor leagues, they break it down into spring training by team. However the team you start out with isn't always the team you will wind up with because demotions from big league camp will push guys down and that trickles throughout the system.