As you've found out, web database is quite different from the traditional databases.
There are no design views; only layout views for web objects. This is probably to ensure that your design can be translated into valid HTML when it get published and avoid issues that may come up if you were to use the traditional design view (e.g. absolute positioning, while possible, is not a trivial implementation on a web page, if I understand things correctly but I'm no web developer so may be wrong here).
Also, you can't have VBA in web objects - you are allowed to put in VBA (as well as any client objects) in a web database but you can't use it in a web browser, only if you open it in Access.
You should be able to use comboboxes - I think what your friend may need to do is put the datasheet in a subform control and add combobox on the parent form... I'm not sure if header/footer will work with web datasheet but just in case - you'd open them in layout, and on the ribbon, there should be "Arrange" tab - on that tab, there's two buttons, "Move up" and "Move down" that lets you move a control from detail section to header/footer section and is AFAIK, the only way to add header/footer.
Hope that helps.