There are pros and cons to each freshman hall. If you talk to current students you will hear each of them say a different hall. If you want to see pros and cons for some of the halls check out the list on the official RPI Class of 20XX Facebook Group, you should be added to that soon. In regards to athletes and rooming, as far as we know you are not required to room with teammates, though highly recommend and most of the time athletic team members room together.
RPI Rooms 
I’m an incoming freshman and while filling out housing I came across the Quad. What is the difference between White I, II,III ?
The difference here is mainly location within Quad (i.e. are you closer to the Union or to Sage Dining Hall, etc.). What is unique about Quad is each room is different, no two rooms are the same. If you check out the room pictures for Quad here you may be able to see some of the rooms in each of these buildings.