If there is one coin daemon running, and at that same server, users will join, then issueing addresses to each users.
Then if I want the users can send & receive to/from his address, when I issue address to user, should I attach account string value to that issues address?
Account in bitcoin daemon is more like a lable string, address is enough to send and receive coins. But if you want to set a new account for each user for management purpose, you can do that using bitcoind's rpc, refer to getaccountaddress api.
getaccountaddress
Returns the current bitcoin address for receiving payments to this account. If <account> does not exist, it will be created along with an associated new address that will be returned.