1.) Installing applications of size X generally requires 2X amount of space. I'm not a dev so I don't know what happens under the covers, but I can understand why (copy compress package, unpack/uncompress and deploy to filesystem)
2.) When you update, it's an all-or-none proposition with the "Update All" button
3.) Because of 1 & 2, if you're low on space and one application is too big to update, when you press the "Update All" button you get an error message and nothing gets updated
So, I now have a red "93" on my App Store icon, and unless I want to manually go and update each non-big app individually, that's how it's going to stay.
Bonus: Loading the icons in the "Update" screen impacts the UI something fierce (as does updating, I guess), so Updating individual apps is an exercise in frustration. This scales linearly with the number of apps you need to update, so at this point I'm past the point of no return and will likely not update an app unless it complains directly to me. Even better, finding the app in the update screen is painful since they're sorted by time and not name, so it's nearing the point where if I can't use your app because you complain to me, and you're not an absolutely essential application, I'll probably just delete you.