the only current sort options in iPhoto are under view menu ==> sort photo ==> by date, by keyword, by rating, by title, manually (only works in Photos display mode with event titles off as of now)
Suggestions for new features o iPhoto menu ==> Provide iPhoto Feedback
You can see the sizes by right clicking on the iPhoto library in the Pictures folder and selecting show package contents -- you should not modify the contents - this might cause iPhoto to get confused and cause problems uncluding losing photos (or at least not being able to see them in iPhoto)