I'm very new to the game, have yet to actually complete one game yet - but it exceeded any expectations I had going into it. OK, that being said - I ran into something regarding cloacking. The ZERG team had 1 Zergling Unit in an area on a planet w/ no base. On the Planet, it contained three areas. I had 2 Marines in an area already on the planet - and utizlied a mobile order token w/ a base and multiple units on the adjacent planet. NOW, the area containing the zergling was a 3-unit limit. I came at it with 4 UNITS from the adjacent planet, and 1 marine from the active planet. NOW, if the zerg team utilized a burrow card - activating cloaking, does the defender then get to retreat his unit first, thus putting his zergling into an empty area on the planet. NOW, am i forced to retreat in a way that keeps his zergling in an area by itself - and have to retread some of units back to the other planet. In this case, should I leave 1 unit into each empty area and attack it with as much as I can to prevent it from dancing around the planet, thus not having it able to withdraw or am I missing something entirely here.

Yeah, your conclusion is correct about putting one unit in each area and attacking with the rest to prevent the 'cloaked' unit from dancing around the planet.