Are all EMR systems scalable to eventually include billing, coding, practice management options such as prescriptions, patient accessible pages for appointment schedule reminders, instructions, etc,?
I would say that most EMR systems are scalable in the sense that companies that provide EMR software also provide practice management/billing solutions as well. So in that sense they are scalable even if they aren't included by default with the EMR system.
For example, Health Fusion's MediTouch EHR is a robust solution that offers prescriptions, patient scheduling, lab results, pharmacy mapping, and more. But they offer billing, revenue management, patient registration, etc in a separate but integratable package called Practice Management. Kareo has a similar structure in which you can purchase different levels of subscriptions that either include only EHR or some combination of EHR, practice management, and billing services.