A. The FAT file systems can be exported, starting with the early 2.4 kernels, but if used extensively, it may cause grief. First, only those operations supported by the exported file system will be honoured. Operations such as "chown", "link", and "symlink" are not supported by these file systems, and will fail. Read/write/create etc., should be fine, as long as the files remain relatively unchanged.
The most serious problem is that the FAT filesystem layout does not contain enough information to create a lasting identity needed for NFS to create persistent filehandles. For example, if you take a file, rename it to another directory, trunctate it, and write new data to it, there is nothing stored in the filesystem that can be used to show that the resulting file is, in any sense, the "same" as the original file, and there is no way to find the new file given any details about the original file. Therefore, the Linux NFS server cannot guarantee that once you have opened a file, you can continue to have access to that file, if the file is modified in the ways given above. NFS may then be unable to locate or identify the file correctly, and so may return ESTALE errors.
Isto é retirado do FAQ do Linux NFS e também se aplica ao FreeBSD (exceto pelo material do Kernel 2.4, é claro). Só quero ter certeza de que você está ciente disso.