If I had a box that was going to samba only then I'd just make a user just for that purpose. If I needed to do some samba work I'd just "su sambadmin" or whatever.
And don't forget that samba doesn't follow the traditional method of users and such. It has it's own set of rules and it's own set of users that you use when you connect using samba.... Usually you can make duplicates of users in the samba config, but those are samba specific and not unix, unless you do something fancy with the PAM stuff. It's kinda like windows were you have the local users and the samba users. If you set rights for one set of users, it doesn't always affect the other group. I am not to familar with samba to tell you anything beyond that. Check out the Samba config file and other documentation.
Other things you may want to look into when dealing with unix style file permissions is a command called umask.
Using this you can set the default file permissions that are used everytime you create a new file or folder....
Also the number stuff isn't that hard to figure out, you said it your self:
read/write/execute(also "search" for directories)
they corrispond to binary numbers
000
421
read/write/execute.
so when it's translated to decimal numbers
7 = read/write/execute
5 = read/execute
3 = write/execute
6 = read/write
4 = read only
etc etc....
then you have 3 groups of users:
owner/group members/everyone else.
in that order..
So when I do a "ls -ld poo" I get
drwxr-xr-x 3 drag users 19 jul 4 04:12 poo
the d means its a directory, the first set of rwx means that the owner (drag) has full rights to this directory, the second set is for people who belong in the group "users"; they can read or search thru this directory, but don't have the right to modify it. Ditto for the last set which is for everybody else.
But what if I don't like that? I want bob be the owner and allow his study group "lusers" full access to it, but deny everyone else from it.
So as root I:
chown bob:lusers poo
chmod 770 poo
and that's it.
Don't forget of course that a directory is just a file that points to other files or "hard links" that themselves point information on the harddisk. So if you give someone write access that means that they can delete or create new files. HOWEVER they can still access those files inside the directory and modify them, since the permissions only apply to the directory "files" themselves. The files themselves still have their own ownership properties. So if someone has rights to a file inside a directory, but have only "x" or search access to them, they can modify the file, just not delete it completely or create new files. Even if you get rid of the read and write rights for that class of users, then can still access those files inside it.
It's a bit confusing at first, but once you realise that the directory itself is just a special sort of file and not a actual physical contaner it begins to make sense. Play around with different file/directory permissions and see what happens.
Here is what I do. make directory "poo" in your home folder. Inside your poo folder run the command "touch crap log floater" to quickly create 3 files. Now go back down to your home folder and become root. Change the owner of the poo directory to root, buy leave the group the same as your normal user. Now play around with permissions. Run like a "chmod 766 poo" then just "su" to your username and try to change one of the files, or "ls -l poo" and do stuff like that. It's kinda interesting what sort of things happen when your rights to the folder change, but you still own the files inside. And don't forget that if you just "ls -l poo" your going to be viewing poo's contents. You must "ls -ld poo" to examine directories directly.
To fully understand file permissions is a bit tricky because your playing on the fine line of abstraction that devides the happy freindly world of files and directory relationships and are beginnning to get into the real meat of how the actual programming works and how software interacts with hardware and all that fun stuff that is normally hidden from you.
But also keep in mind that Samba has it's own set of users and groups that are completely independent from your normal unix users and groups. I don't like it, but it does make it easier to provide windows user support.