They signed Justin Durant to a 2 year contract(can't find the salary). He'll play WILL LB for the Lions. Good signing. Young and athletic who can play 3 down.
The Lions are going after Jonathan Joseph and Stephen Tulloch. With the cap space, I'm not sure if they have enough cap space to sign both players. Joseph is likely to be signed anywhere from 7-10 mil a year and we don't know until Nnamdi Asomugha sets the CB market. The Lions have already offerred Tulloch 6 mil a year(w 10 mil guaranteed money).
So far, good start by the Lions by filling one of their bigger holes, OLB. I think that if the Lions don't land Joseph, I expect them to re-sign Chris Houston because I don't think the CBs available in the FA market are better than him.