Ok as you can see the current tv is too small so I got a 49" where should it go? Long wall or short wall?

It depends on where your furniture will fit. It should be mounted where you can sit and look at the tv straight on. I would not not mount it on the short wall if that's where the couch will stay.

If I put the tv on the wall where the couch now is, I could put the couch on the wall across from the tv?? So, the couch would face the tv.. would that lol ok?