Will I be ok updating to Mavericks (using Aperture 3.4.5)?
Aperture 3.4.5 is working with Mavericks, that should not be a problem. Just take the usual precautions and make a current backup of your mac.
But you should check, if other applications or plug-ins you rely on, like scanner drivers, printer drivers, etc, are compatible with Mavericks.
I'm slowly debugging the lib (exporting sublibraries, reimporting all photos, etc), but it is a very long term project.
That looks like a daunting project. What kind of problem is there with your Aperture library? Have you tried all repair options? Repairing and Rebuilding Your Aperture Library: Aperture 3 User Manual