I don't know if they still make them, but Living Textiles made muslin wraps that had a bit of stretch in them, they were awesome. .
Yes they do, I got some from Baby Bunting, you are right, they are excellent!

Snugglebum make great PJ's for summer. DD wears them. You can also use light PJ's with a light Gro Bag. That's what I did last year and it worked a treat.