Welcome from Ontario, Canada. Cute top!
I would use a 80/20 batt and look at the package to see how far apart the quilting lines can be. If you plan to try and quilt it yourself, you will need some method to baste the top, batt and backing together before you start. You can use fusible quilt batt, 505 basting spray, pins, thread basting etc.
Once you have your quilt sandwich made, you can use your regular foot and off white thread to stitch down the seams of the coloured rows and the center of the off white squares.
If you decide to have it quilted by a long armer, ask to see samples of their work, get a price for all over quilting or custom quilting. Ask if they want to use their own batt and backing or if you should supply it.