If you're sending this out to a longarmer, I'd contact them and ask what they would prefer you to do.
For seamed backs it is much better to have the seams lay the same direction as the rollers. If the seams are perpendicular to the rollers, as the quilt gets rolled those seams pile up and make an uneven spot - some of the quilt will be tight at the seam, loose between the seams.
Be sure to remove the selvedges from the backing.
What I'd do myself is to have three strips across the width of the quilt - that's because my 10' frame won't load a 108" quilt plus the 4" each side needed to load on the frame. If your longarmer has a wider frame, three strips lengthwise would work.
If you're hand quilting or quilting this on your domestic machine, you can be as creative as you'd like!
I would be cautious of borders as it can be tough to ensure they get matched perfectly to the top as it is loaded.
Hope this helps, Good luck!