How to see what needs a software update before requesting update

I just upgraded my OS to 10.9.5 on iMac 3.06 GHz, Intel Core i3. I lost access to iPhoto, was told it has been replaced by Photo and will get installed via an update. Ran the first update (I'm not used to not having a choice about what I update). Now the thing tells me I have one more update, but won't tell me what needs it. It lists all the applications it updated last night.

? How do I find out what it wants to update BEFORE I do the update?

? How do I get the application that replaces iPhoto ??