New to the sport, I am trying to figure out how transactions work.

I understand that minor league contracts, signed upon the drafting or acquisition of a player, last 7 years. Is that so?

If the MLB affiliate 'purchases the minor league contract' of a player, the player goes on the 40 or 25 man roster, right? They can then be switched between AAA and the show until they are out of options, traded, designated for assignment or placed on waivers, right?

Ok, so here's an example: http://www.sportsnet.ca/baseball/mlb/players/Phil_Hughes/

I'm looking at Phil Hughes. He was drafted in 2004, so that would begin his 7 year minor league contract? He was assigned to minor league camp in 2007-- does THAT begin his 7 years? I'm confused.

The Yankees purchased his contract from AAA in the early part of the 2007 season, and then signed him to a one-year contract (I guess a MLB contract) for the 2008 season, now completed. So now, he does not have a current MLB contract, correct? But the Yanks still 'own' his AAA contract running from (help me out here) when he was drafted in 2004, or when he went to minor league camp, in 2007? OR, does signing him to a ML contract for 2008 eliminate his 7 year minor league contract altogether? He's still on the Yankees 40 man roster, so I assume he is NOT a free agent.

A DETAILED explanation on these matters or recomendation to a good source to learn would be appreciated.

Cheers

df