Speaking of the clipboard, this would only take effect if you've copied the information to proceed a transaction, correct? So if you make a mistake, you'd already know that it's compromised, and it won't affect other wallets because you'll be more careful next time. You might even end up reprogramming your computer to eliminate that malware. What I'm saying is, you will lose the balance of one of your wallets but the others will be safe.
This is correct except that the clipboard hijacker malware doesn't affect the wallet itself so it can't steal all your coins. What it does is just changing the address you are sending to with the address of the attacker. You will lose only the coins you are intending to send not all the coins on the wallet.
The safest thing to do is to always double or even triple check the transaction details before clicking the send button.