May employees engage in organizing efforts and hand out literature regarding Unions on company property?

Yes.  Employees may discuss unionism and solicit their coworkers, if these activities occur before and after their shifts or during lunch and break times; employees are not entitled to engage in these activities when they should be working.  It may also be permissible for an employee to give coworkers union flyers or authorization cards in a lunchroom, locker room, or parking lot, but not on the work floor, where papers could create a hazard.