can i set a quota for each MAC address assigned on this TP link address ? is it possible ?

i know we can set a max. speed for each IP / MAC address, but can we set a quota like 10gb ?

http://www.gargoyle-router.com/ ... if i flash to this firmware , will i have difficulty in vlan tagging ? i juz need unifi for broadband , IPTV and others is not important for me.....any advise ?

what if i do not want to do vlan tagging , will it affect my unifi broadband ? i juz concern on broadband only...

openwrt can't do quota management right ? 

OpenWrt has no easy user interface for allocating bandwidth per IP (aka, you can say, quota management?) There's the alternative though, that is, gargoyle routers, which is based on OpenWRT, that is capable of limiting traffic based on the rules.

Apart from that, if you really want to use OpenWrt and still manage bandwidth/user, you'd have to learn tc and linux scripting. Not to scare you, but be prepared to spend a week to learn it.