Your first question has been more or less covered you more or less leave read only rights for your parent folder and whatever rights are needed for the child folders below it. I am taking it that the parent folder is the one that is shared.

For the second point there is a folder called "all users" in "c:winnt\profiles\ " it is in this folder that you copy all common icons for your users. This can be done in many different ways. If your park isnt too big you can make a little bat file which will copy your links to this folder on each computer.
A little aside dont forget when you create your shortcuts to make sure that they point to the network computer. A silly point i know but ....

Another option is if you use scripts to connect just add a line that copys your links/shortcuts to the required folder when the user connects. This avoids modyifing the registry on each computer.
it could read like this :
net use m: \\serverscource\networkshare
xcopy m:*.* "c:winnt\profiles\all users\desktop\*.*"

you might want to check out the paths given in the lines above as I am writing this from memory but the theory should be sound.