It is your quilt. It seems to be a good size so unless you want to make it bigger I think it is okay without one. Many scrappy quilts I see do not have boarders. But if you do, I agree with a darker narrow boarder and then a wider outer boarder.
For quilting I think a fan or clamshell would be appropriate. But with scrappy quilts it doesn't show that much so you could do about anything.
By the way, I forgot to start with, I think it is a lovely top.