No, you can’t create users directly, for that first you should have to create contact for a particular person. From that contact list you can create users who has login access. You will see create user button on contacts list by clicking on that button the particular contact will be converted into user who has login access. You can see the converted contact person in users list which is in user management.
Yes, Laraoffice provides such a wonderful option called permissions. If admin wants to give some permissions to some users not for all at that time this permissions feature is very useful he can easily restrict anything at the users area. This permissions feature you can find in users management ->permissions.