Sorry, hector, we don't have a list of what's missing from WebForms. For the Save(), since the business objects are generally listed as properties on the ApplicationBasePage and stored in session variables, your best bet would be to write a protected Save() method on the ApplicationBasePage to save all of your business objects from there. For the IInitOnFormLoad objects, using the PageLoad and testing on IsPostBack would be best for initializing your stuff.
V2 have better web forms controls, but if anything, the business layer is more de-coupled from the UI. There isn't a dependence upon one UI or another. WPF is just as different from WinForms as WebForms is.