During installation, the router sent several data packets to an Amazon server in the US. These packets contained the configured SSID name and password in clear text, as well as some identification tokens for this network within a broader database and an access token for a user session that could potentially enable a MITM attack.
Linksys has refused to acknowledge/respond to the issue.
That depends entirely on the auth system, but you can use a separate credential to retrieve the password (using something like a PAKE algorithm)