Enhancing an application based on browser features

Your team has been hired to develop an ASP.NET MVC application for an insurance agency. The agency has both office staff and sales staff. Office staff members use Microsoft Surface tablets and sales personnel use iPads. When visiting with clients and prospects onsite, sales personnel must be able to use their devices to check in with the main office to place orders and ask questions of the office staff. The office staff needs to be able to respond to questions, but not ask questions. The applica-tion should also maximize screen real estate on both types of devices.

What should you do to ensure that both types of devices can use the application?
What approach should you take to provide different functionality based on device?
What kinds of issues could you run into when making functionality issues based on device?