They are considered semi-pro, that's why collegent players can play without risking their eligibility. I'm not sure there is a cap or a limit on how many paid players a team can have on their roster.
I think Dunivant was a must sign. I know a lot of people are excited about Cochrane. But I'm not sold he's ready to play every game yet. Plus I still think Dunivant is still a good MLS LB.
I started up a 2013-2014 version of this thread, if you could please continue the discussion over here - https://www.bigsoccer.com/community/threads/official-2013-2014-roster-moves-and-rumors.1996645/