Could anyone explain how important these are. With the new financial constraints player selection is crucial and i want to fully understand how to compare players.

When looking at some of the players who have 5 star ratings their stats dont look to much better than a 2 star prospect. and vice versa. Is the rating what i should be looking at?

Also how important are the talent ratings?

Player rating is how well a player knows how to play a position. That does not mean he has got the skills to do what he in his head knows.

Talent doesn't change, rating does. As a new team, you should pretty much ignore natural positions and rating, as in your first season, there will be so many bot teams, that it won't hurt you to play players out of position. Slowly their natural positions will change, so you should play your players in the position where their skills indicate they should play.