It's impossible support two WAN connections in same time on this router. You can see SMB solutions with two WAN ports.

Have you seen FAQ - http://www.tp-link.com.pl/article/?faqid=639

Region : Poland Model : M7350 Hardware Version : V1 Firmware Version : ISP : Plus or Play http://tplink-forum.pl/opinie-uzytkownikow-opinie-ekspertow/tp-link-m7350-3673 - you can see private testing...

Do you have public IP address on WAN port?

It's impossible in this configuration. WR710 is only Access Point. You can configure it on main router.

Have you seen Parental Control feature? http://www.tp-link.com/en/article/?faqid=350