When a card is suppose to be upgraded do you remove the card being upgraded from your deck? Then the card gained from the upgrade, are you allowed to play that card? If you upgraded a card already on the bridge, can you play the gained card?
Yes, you remove an upgraded card from your deck. No, you are not allowed to play a card immediately when you gain it. Normally, when gain a card it goes to your discard unless the card specifically tells you otherwise. No, if you upgrade a card from your bridge, the gained cards normally go to your discard area, unless the card says specifically otherwise.
From the Rulebook2.0 on Bandai's website, (page 24-25 Glossary):