My friend, unfortunately I cant send you the link because I read that very long ago and I really don't remember where was it! But provinces nominate applicants and they try to keep them in their provinces. For example in 2013 SINP tried to call many nominated applicants who came through SINP to Canada on 2011 & 2012 and asked them to provide their house utility billing like electricity,... And in this way they tried to be sure all pnp applicants stayed in Saskatchewan province in that time!
About answering your questions:
1) NO! because you uses pnp nomination to get 600 extra points and because of that you should stay in Saskatchewan. And don't forget that in your EE profile you SHOULD select SK as your destination if you want use SK PNP in your EE. Please don't ask about the link because it is a clear fact like a blue sky!!!
2) Based what I said before you can move to other provinces after a period of time (for example 2 years)
3) If you couldn't find any job in Saskatchewan and you can find a job in other province then you can go there (You should provide your contacts with employers inside SK every time it is needed in future ) but it is impossible! because Saskatchewan has the best job opportunity in whole Canada! Jobless rate in SK in 2% but it is larger in other provinces!