I've had a FFL license before and am looking into doing it again. Where I live now requires a variance from the city planning & zoning because it's residential. Has anyone had to deal with this and have any input on how to word my request? Any help would be appreciated.

So many variables. How's the political climate in your area?

It's gonna be up to your city and their inspectors. You may have no problems, or may have to tangle with bureaucrats for weeks or months, depending on the people in your city planning/zoning department and how your particular laws are worded.  In the end you may never get such a thing approved, I've seen all different outcomes.

First read up every thing you can on the process and the laws so that you know what you're actually applying for and what you'll be dealing with.

When I got mine, I had to keep calling and writing and pointing out that "it wasn't forbidden, therefore it's legal" before they eventually relented and issued me my "home occupation permit", which is the legal term for it here.  Took me about six months.

Had to go that route when I moved to my current location
It entailed a public hearing where my current neighbors were all invited to make comment about my request
My immediate neighbor sent a very supportive letter
One of the other couples on the street only objected because they didn't want their minor children to see people carrying guns in and out of my place and having to explain to them about guns at an early age
I actually had board members speak up to that and say they'd grown up in a rural village and the sight of a gun hadn't traumatized them.
So for the first year after I moved in my regular customers were all told they had  to bring stuff into the shop in a gun case.
That family has since moved, so it's no longer an issue.
It helped that its been a few years since the last FFL in the village closed up shop and the village has recently been trying to promote small town business start ups.

I had to get a variance here in Boise.  It consisted of me looking up zoning requirements before I called so I would have some knowledge of what they expected.  I then called and talked to a nice lady.  I indicated that it would not be a retail location but rather a gunsmiths location.  My focus is primarily on transfers and repair, thus the gunsmith license.  They indicated that I would be classified as equal to a piano teacher or hair cutting business operated in a garage and that zoning requirements were not applicable if I kept the area used to below 500 square feet. The trick was to keep retail out of the equation.  Thats my story for what its worth.

i spoke with my building inspector.  he was very helpful and forthcoming.