I'd be ok with Cooper in that role. All though like someone else said he should be a non force user... a strict younger version of Han. He'd be good playing that cocky yet likeable guy with the big smile... has worked for him before. All though still kinda hard to imagine the nerdy guy from Alias being as popular as he is now lol.
well we don't know who he would play if he is Han Solo's son. To assume he would be Jacen solo is a bit premature at this point as we don't even know if they will do the Solo twins. There is no real reason to really think that they would
We know it's going to take place about 40 years after ROTJ and it is NOT based on any existing EU story.
In the EU 40 years after ROTJ both Anakin Solo and Jacen Solo are both dead.