The system requirements for Lion are spelled out on Apple's site but there is not enough information about which applications it is and is not compatible with.
Application compatibility is better discussed with the software manufacturer, as it is up to them to update their software to work with the new OS. IOW, you should try contacting Microsoft regarding Office 2008.
iPhoto is another matter, but until Lion is released, we probably won't know much more about iPhoto 09 compatibility. Being that it's from Apple, IMHO I think it will work. However as Ziatron suggested, the machine where my iPhoto library sits (which is running iPhoto 09,) I will not be upgraded to Lion immediately because of the same concerns as you.