With regards coaches there doesn't seem to be a cap carry over etc? I've only ever signed a coach until his contact runs out then I just renew it. I got the impression coaches are very very little effect in this game so I've always just kept them ticking over. ...
So I typically offer all of my coaches new 6 season contracts during free agency 1 to minimize poaching. I only give them like 1 more dollar or something. There is no dead cap or anything for coaches, you can fire them at any time you wish, so there really is no reason to give them anything less than 6 seasons. Typically for position coaches I look for young guys that are improving at a rate of 3-4 per season.
But if you are hiring young guys you need to make sure they are progressing. Some of them flatline, and some of them even go backwards! Remember to check up on them during the season to make sure they are improving like we would hope they should. For obvious reasons, there is not a lot of history for us to go by.