I think if this was my project I would use an RPi (or a cheap laptop) and an Arduino. The Arduinos are great for controlling things and collecting data from sensors but building a web interface would IMHO be a great deal easier using Python on an RPi or PC.
A simple serial interface between the Arduino and the PC will allow a two-way flow of data and instructions.
If you are interested in using Python have a look at the Bottle web framework. It makes the creation of a simple web server (or client) very painless.
...R
Python - Arduino demo
Serial Input Basics - simple reliable ways for an Arduino to receive data.
Planning and Implementing a Program