If I transfer BTC to a friend/family, they now know my wallet address, correct? Does this mean they can see all the transactions I have done from that wallet? It seems like wallet information is public except for identity, but that would be forfeited once I make a transfer, right?
^ BTC transaction was designed for having transparency and this is not all anonymity, it is pseudonymous. Once your identity is linked to that address your identity will be exposed and you can hide all your transactions not unless you will use third-party tools that can mix your coin before sending it to the destination that wants to hide, like suggested above it was a BTC mixer. All information in your wallet will be exposed too once they know what wallet address you have used. But I don't understand what is forfeited, no one can get it if that is your coin, remember always store your BTC in a wallet where you own the private key.