I would like to share image previews
Does this mean you don't want to share the actual images, only the previews?
I don't really know any easy way to do this. I know you can use a plugin to extract the previews as JPGs and then transmit those.
Is there away to share a Lightroom catalogs setting between users and platforms that will retain the Lightroom settings?
You could write the metadata to XMP and then transmit the images and sidecar files via FTP, other Lightroom installations will be able to read the develop settings and then render the image properly (assuming you have the same major version of Lightroom on each computer, i.e. Lightroom 5.X can read Lightroom 5.X edits, but Lightroom 3 will not be able to read those edits unless you use an earlier process version)
Look at this thread Can I edit someone else's LR Smart Previews remotely? which is answering the question from the outsource worker viewpoint. The key bits are the Export To Catalog and corresponding Import from Catalog steps, and you can include the originals or use smart previews as your circumstances require.