Can L/O for the MAC process documents converted or created by L/O for Windows?
Yes. LO and the default file format (OpenDocument or ODF) are both platform agnostic. So long as you are creating and opening documents saved in the native formats (ODT, ODS, ODG, ODP, etc) you should have no problem, regardless of platform. There are however cross-platform issues with non-native format such as DOC/X, XLS/X, PPT/X, etc, although for the most part these are handled OK.