Regarding the masquerade, please try adding this to Network → Firewall → Custom Rules:
iptables -t nat -I POSTROUTING -m tcp -p tcp -d 10.y.y.1 --dport 80 -j MASQUERADE
iptables -t nat -I POSTROUTING -m tcp -p tcp -d 10.y.y.1 --dport 50040 -j MASQUERADE
iptables -t nat -I POSTROUTING -m tcp -p tcp -d 10.y.y.1 --dport 50042 -j MASQUERADE
iptables -t nat -I POSTROUTING -m tcp -p tcp -d 10.y.y.1 --dport 50043 -j MASQUERADE
iptables -t nat -I POSTROUTING -m tcp -p tcp -d 10.y.y.1 --dport 60000 -j MASQUERADE
Don't forget to replace 10.y.y.1 with the actual IP. :)
But I must admit, I may not be getting the full picture here. If it doesn't work, can you send me a Troubleshoot file via private message? It can be downloaded from the System → Administration → Troubleshoot page.