Think so 
I want to keep the quarter inch tubing I have already - is that correct?
Oops, yes three please unless the fittings are the same on most ro systems then I could take one off an old housing.
Yes these will work with 1/4" tubing.
I will pass a message on to the fulfillment team to make that 3x 1/4" fittings
The ones from your old housing will probably be 1/8" screw thread so would not fit.