It's great that you are taking an initiative in building/replicating one like EZ-Robot. I would like to add a few things which helps in building a robot:
2) Cost Factor.
By simplicity I mean choosing the right hardware that actually helps your prototype to be built faster and the testing/debugging is easier. For instance, if you choose Raspberry Pi with a Wi-Fi module (I saw one at Adafruit stores for around US$12), the whole setup may be build under US$50. Adding computer vision (I think this will boost up the investment price) since it already runs Linux on it, helps in achieving the ease in usability and development. Now you have a system that can be controlled by many components. Using a Bluetooth module with Raspberry Pi is much cheaper than you may think. Chinese modules are cheap, like US$5-US$10. Hereby you will have an independent robot.
But as you say, you wish to remotely control, the Arduino keeping your PC (since you mentioned Visual Studio), this can be done easily by adding a Wi-Fi module, but Xbee costs are really high, and then use the HTTP protocol to control the robot. The Arduino will be fed with some input, like say numbers ranging from 1-100 that may accumulate 100 tasks. Like move left, right, up down, turn on the light, etc.
So essentially make sure, which development board may help you serve the purpose easily.