6 months is no problem...I've done it (and much longer) many times, both before I was married to a Filipina and after. Just keep extending your visa once you're there. Very easy. Travel agents there will also do it for you for a small fee.

Don't worry about the dates on your ticket, as long as you have a ticket OUT, that is all they're looking for, and they know that you'll be able to get visa extensions to cover it. Just don't OVERstay.

It will not affect your wife's spouse visa at all, rather it will help, because you will have demonstrated that you have a genuine relationship.