Well it could just be that they're in heat...you never know sometimes. Many of my does' udders enlarge when they're in season. What do you mean the back two nipples? Do your goats have extras? Just curious...
Ideally, yes - you'd want two kidding stalls/areas for them. However, the ideal isn't always possible. Case in point, stupid me set eggs to hatch last weekend, and one of my goat stalls doubles as a chick brooder...so right now I just have one 10 x 10 stall available and three does due any day. Yup, they're having to share. Luckily, all of my goats get along fairly well so this isn't a huge problem, just not my ideal.
Looking forward to pics. It's too late now to worry about washing those teats, just don't make a practice of expressing them unless you have teat dip.