Thanks for coverage of the topic.
Now I understand why js loading on request is happening in different requests.
Indeed simple hack with list of packages on init and incremental downloading afterwards should do the thing.
I'm wondering if those popin.htmls must be loaded even if dialog is not being loaded, but I suppose that's redundant requests you were writing about.
As an extra or a tweak trick you could provide css sprite/map for images/calendar/*.gifs which would give one request (like Google does for their navigation) :)
For best results, use the Firefox browser..