1. Is there a way to update the VPN client from the latest version from the gateway?
Yes. The process is listed in the document titled "ENDPOINT SECURITY CLIENT E80.72 AND HIGHER FOR WINDOWS" found in the Support Center. Page 29 "Automatic Upgrade from the Gateway." We just completed an upgrade for unmanaged VPN clients using this method 2 weeks ago.
2. Is there a way to push out a new configuration to the client?
Best I can find there is not a way to do this from the gateway. The document ""ENDPOINT SECURITY CLIENT E80.72 AND HIGHER FOR WINDOWS" does cover a way to do it using client side tools. Page 35 "Updating User Sites with the Update Configuration Tool"
Hope this helps.