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?
If you send Bitcoin directly form your wallet then receiver will be able to know exact amount of coins you have on your address or addresses.
Good address management can reduce this, and you can also use coinjoin or mixers like ChipMixer to remove connection with your original address.
Sending coins form your exchange account is also an option, but much more risky because they can lock your account and freeze your coins at any time and for any reason.
Yes, as per the indications above there are options with mixers to mix up your address and in a way make it indistinguishable. That's a bonus working with Bitcoin also.
In a normal transaction once they receive the transfer they'll obviously see your address and if they wanted to they can check it on the explorer to see everything you've done with that address what went out. what came in, current balance.