Two firewalls is not a good idea. They tend to clash with each other & can have side-effects, & results in less security, not more. So decide between XP or McAffee firewall & disable one & configure the other to allow LW full access; see User Cant Connect - LimeWire (click on blue link)

Also, your model router is a reknown "lemon" by Linksys. It has firmware problems which they never bothered to repair. Port forwarding is definitely more reliable for it than UPnP. You can fix the firmware yourself but only if you know what you are doing (instructions are on the forums.)

To find Java version, go to LW's menu bar, Help menu, About LW. Another way is to go to Tools>Options>Bug reports & run a report. The report will show the Java version.