The ORIG_PATH_INFO vs. PATH_INFO isn't an OJS bug, it's more of a configuration issue -- web servers should be sending data using PATH_INFO, but in some situations they're slightly misconfigured and you need to use ORIG_PATH_INFO instead. We're not likely to add a work-around for this to OJS, but if you're using patch-based upgrades, you'll be able to use any future release of OJS without having to re-fix this issue.
To fix the second issue you describe, try disabling the session_ip_check option in your config.inc.php; if you're behind a proxy farm, it sometimes appears to OJS that you're attempting to connect to the same session from multiple IPs. By default, OJS treats this situation as a potential security problem and requests another login.
Open Journal Systems Team