I don't quite get what changes you are suggesting here for now, I'm really new to OpenWRT. It works, IPv6 works but only for a limited time (always varies), and the client which had the IPv6 address suddenly loses it, and there goes the connectivity with it, IPv4 still works. I'm not really concerned about reliability here, but I have to say it is way better than the Stock Firmware (It used to randomly reboot and slow down, have ping spikes, also took way longer to boot from a cold start), only problem I have now is the clients losing IPv6 connectivity after sometime.
But overall, I'm really happy with what OpenWRT has to offer and I will be tinkering with it in the coming days for a long time.
As for your 3 suggestions, yes I have found some posts on OpenWRT forums and have tried some of them with no success, will be doing more in the future.
Also, what does your network setup look like? If you don't mind sharing. Thanks.