It sounds like a good plan. No need to be scared. We all had to jump in at some point.
One idea on the stripes is to miter the corners.
The key to the quilting is to do good preparation.
When your top is finished, press it well. Likewise with the backing, press it well and make sure it is at least a few inches larger than the top.
Make sure the batting is larger than the top but smaller than the backing.
I tape my backing down once it is nice and flat on the table. Then I carefully center the batting. Lastly, I center the top and pin baste it. I make sure that the pins are no further than my hand width apart, and that they are not on a seam that I plan to stitch over.
Once the quilt is sandwiched and pinned, you can move it around without worries. Check the back to make sure there are no pinned puckers.
You could quilt a grid pattern. Just go slow until you get the feel for it and take lots of breaks to keep your shoulders from tightening up.
It will be pretty and your friend will love it. No worries about the "perfect" SID - you should see some of mine (all wonky) and NOBODY even noticed.