Nice job with that pattern! It really is that easy, everyone should try these
To answer the questions, the diva cup (i use a mooncup, similar thing) works great!! I love it, and will never go back. I am buying one as a gift for my sister too, since I wish I'd known about it earlier.
My pads are flannel too, but just zigzagged around the edges (or serged), I like to use water proof fabric like pul (polyurethane laminate) For a backing, but it's not necessary as long as you change often.
When I'm out, a plastic bag in the purse works great. I don't rinse mine, I put them in a lidded container in the laundry room til wash day. They do dry out, but I don't have stains.