This info used to be posted on MiLB.com but now I can only find it in the Google Cache - so they must have updated their page links
Triple-A--First year: $2,150/month, after first year no less than $2,150/month
Class AA-First year: $1,500/month, after first year no less than $1,500/month
Class A (full season)--First year: $1,050/month, after first year no
less than $1,050/month
Class A (short-season)--First year: $850/month, after first year no
less than $850/month
Dominican & Venezuelan Summer Leagues--no lower than $300/month
Meal Money: $20 per day at all levels, while on the road"
Those numbers above are why I don't have any issue whatsoever with draft picks doing everything they can in their power to get as much money as they can with their first contract. They make virtually no money until they crack that big league roster and can start making $380k plus a year.
The rest of your answers can be found in the basic agreement - plow thru it, it's pretty interesting reading. The latest basic agreement hasn't been posted online yet, but here's the basics according to the last one