I just added more ADA on my Yoroi Wallet while staking in a pool. Will the new ADA be automatically added into the current staking pool?
And do I need to withdraw my rewards in order to restake it?
New ADAs will be added to the pool automatically but they will not be considered for 1 epoch, because snapshot need to be submitted. You can check here how the staking timeline works.
Rewards are automatically added to your wallet, you only need to withdraw if you want to spend them