As far as rewards go, we will receive rewards in Heaven according to our works, so there will be different rewards for different workers. Paul encouraged us to work for God, not because we had to in order to be saved, but because we were saved. He taught that we were saved by grace. In other words, there is no work we can do to get to Heaven, because our salvation is based on what Jesus did on the cross.
Jesus' half brother James taught that we should work, and that our salvation without works was "vain", or in other words, ineffective. Some think that Paul and James taught opposite doctrines, but in truth James just clarified and reinforced what Paul taught.
If we could earn our way into Heaven by what we do, then Jesus' death on the cross was all in vain. Our entrance into Heaven is based completely on our faith in Jesus Christ as our Savior...nothing less, nothing more.The work done in His name is an added bonus and a product of our love and devotion to Him for what He did for us.