[iLinx]

1) Save a unix time stamp in OnGameModeInit in a variable and then to get the uptime just get the current timestamp and subtract the startup timestamp from it, and you'll get the uptime in seconds (give or take 1 or 2 seconds).

2) Just create a MySQL query that saves their time when they logout on OnPlayerDisconnect using, again - best way a unix timestamp, since it is easy to convert it into different time formats.