These look like great purchases for your climate and your needs. I especially like the EF lantern dress (for all the reasons you've said), and the tiered dress. Cool, easy to wear, and sun-protective to a degree.
I'm sure you'd get a lot of wear from the turquoise top for the same reason. Also, I find the cotton gauze does not require ironing. I wear a shirt I got from the GAP a few years ago in that fabric a LOT for casual at-home summer stuff. (I returned an identical pink one because I realized I just won't wear some shades of pink, no matter how flattering, LOL!)
Re the two Chico's dresses pink and blue....while of course I am your partner in cobalt love and it looks amazing on you, I'm actually liking the pink a bit more for this occasion (a grad). It feels very feminine and festive and I love the drop waist, which should also help with your midsection woes. At the same time, it might be worth considering which you'd be likely to wear more. Is the blue one likely to be hotter because it has longer sleeves?
I think the bungee dress could make a great cover up. Smart idea.
The EF skirt sounds very cool and practical if you can live with the crease!