General rule for Star Alliance fares...it's +1 bag, but only if you purchase the fare with the first bag. So it's not 0+1=1....but only 1+1=2!
You will have access to the lounge, no issue with TAP.
For better seats, the best is generally to ask at the gate, they will write manually your new seat on the boarding pass. I speak of personal experience. They cannot change your seat without charging you, reason for doing it manually with a seat/row available on boarding.