How can I forward texts to my  tablet and reply back?
If you're in the USA, use Google Voice - it allows a user to make voice calls while on WiFi and also allows sending / receiving SMS.

Also look at Tablet Talk for your SMS needs at least. In early development, there's also Phone Link

If you're working on your tablet, I believe the simplest solution for voice calls is to have a bluetooth handsfree paired with your phone so you can make and receive calls.