Welcome to the board! You have some good suggestions here. Your enthusiasm is great, but as you have learned, it's a good idea to finish a test block for your project before you cut out multiples. Go ahead and finish one 16-patch and see how it fits. If it needs to be bigger, try to decide how much you need and add a border. Remember you will be bordering all four sides, so if you think you need two more inches, the borders would be one inch on each side. You also need seam allowance, so your strips would be cut 1.5" wide.
Do post some pictures - we love them! And come back if you have more questions, newbie or otherwise. There are lots of helpful people on this board.