Do you think Rand has put one and two together and realizes he and Galad are half brothers yet?

Well yeah, thus the reason he was freaking out thinking he was realted to Elayne. He asked some noble (I forget her name) to tell him in terms of a farmer if he were closely enough related to her for them to be allowed to marry (of course it was in some backhanded way) and was relieved when she said no.

 

Yes he knows

Whether this information will be revealed is an entirely different story.  Dyelin has her suspicions, but I think Rand will want to keep it under wraps since he plans to die at TG.