It is always interesting learning more about these signings because these are guys who are getting a small amount of money as they try and pursue their dream. The players get a small signing bonus, but usually nothing else is guaranteed. They are signed to multi-year contracts at the league minimum (starting at 405,000 in 2013), but nothing aside from the signing bonus is guaranteed.
Matt Maiocco reported on signing bonus numbers for a few members of the 2013 class. According to Maiocco's source, Lawrence Okoye is getting a $3,000 signing bonus, while CBs Darryl Morris (Texas State) and Lowell Rose (Tulsa) lead the way with signing bonuses of $8,000. Those are not huge differences, but it shows some level of intrigue by the team. We'll see if any of the higher signing bonuses boost a player's chances of making the roster.