You don't have to worry about b) point if the file permissions are rw?rw?rw? in your server and client machines. So, check permissions for /home/sys and /home/sys/* in your server and /home/***/*** and /home/***/***/* in your client... changing them to 777 could solve your problem.
But I will try to explain it more or less:
Users in your server and client machines have a id number (the id command will show you which is your id and your group id). So, let's say you have a user in your server named dunmarie and that user have an id equal to 314. Let's say you have a user named dunmarie in your client machine too, but this user have an id equal to 302. And let's say you have a xxxx user in your client machine with 314 id (the same that dunmarie user id in your server machine). When you mount the /home/sys in your client machine, all the dunmarie's files in that server's directory will be xxxx's files in your client machine because they have the same id.
The same can occurs with the groups.
It's obvious you can see the owners, the owner's groups and the file permissions with a ls -l command in your machines.
But like I mentioned above, you have not to worry about it if the files and directories have write permission for everybody in both server and client machines.... and then... your problem would be due to something else.