qbquilts

Very pretty. To answer your questions:

That depends. Do you want the block to shine or the stitches to shine? This is similar to deciding what thread to use when doing regular quilting. If using a thread that blends with the fabrics, you tend to lose the quilting/crazy stitching and the eye sees the block as a whole. If you use a contrasting thread, you tend to see the pieces/stitching before you see the whole. If you have enough fabrics, maybe you could make a sample block of each (and then use the one you don't choose as some type of accent - pillow, on a diaper bag, etc.)

I'm a border person, so I would probably say yes. I think borders frame and finish a quilt and almost always use at least one. But some quilts look great without a border and it's often up to the quiltmaker if the quilt needs a border to look finished or if the border is needed to get to the desired finished size or if the border makes the quilt bigger than desired. So it's up to you.

I would either do it the method purrfectquilts just posted or add the border in the same method you assembled the quilt center - either using the same connecting strips as the center, contrasting ones to both the center & the border, or connecting strips the same as the border. Your choice depending on the look you want.