Gorgeous photos of wonderful spiders! Always a treat.
If I'm not mistaken, that small spider is a juvenile Steatoda sp. that was hanging around an empty egg sac (not hers, but some other spider's). The exuvia you later found also looks like a jumping spider, but it's really difficult to tell with all the webbing obscuring it. Chances are the other spider ate the juvenile Steatoda before shedding.