Just curious, are you asking these questions because you think you have a sniffer installed? Or are you just asking hypothetical questions for your own information?

If you think you do have a sniffer installed, what Operating System are you using?

f so, can someone down the line access those packets and see the passwords and browsing information the packet sniffer obtained? I'm just kind of paranoid.
To answer this question: Yes. Otherwise, it would be kind of useless to install a packet sniffer