That's stunning!
Personally, I wouldn't pull the borders apart, I think it looks good. Lining up those points (yep, I see what you mean) will make it *too* symmetrical, if that makes sense. I like the borders as they are, just add plain squares to the end to reach the edge.
As for quilting, no idea sorry. I'm still a beginner, I'd be inclined to just stipple it simply. :-)