I debated getting the 101 Book, but all of the same material is online, along with more photos which are bigger than the ones you get in the book. But the Bentley manual is a must have for all Boxster owners in my opinion.
The workshop manuals are usual expensive to buy, and unless they have have been meticulously updated, a lot of used ones are often lack most or all of the updates. As JFP in PA has noted in the past, if you do download the online copy of the workshop manuals that are floating around online, be aware that a lot of the values and smaller details have not be updated over time, and a lot of the stuff in the online copies is incorrect. That said, I find them useful for certain diagrams that are not available anywhere else.
You can always get per article or per hour access to Porsches online technical system:
https://techinfo2.porsche.com/PAGInfosystem/VFModuleManager?Type=GVOStart