Hello Ishaik,
About PFS - please check Vikas's post again. PFS is not a checkbox in ScreenOS. It is a part of your proposal set. In your screenshot, I see both proposals use Group-2, which means PFS is enabled. If you click the drop down, you will see some proposals (shown already by Vikas) which have 'no-pfs'. As long as you are using proposals that do not contain the no-pfs keyword, PFS is enabled.
Since the other end is a non-ScrenOS box, I'd advice that you add individual proxy-IDs for every subnet you like to talk via the VPN. If there are too many subnets, see if you can configure a 0.0.0.0/0 proxy-id on both sides.