ordering ro di kit

[e46er]

http://www.thefilterguys.biz/ro_di_systems.htm im just getting ready to order the $135 5 stage 75 gpd (second one down)

now jsut to be clear ive never seen one of these before, but 4 canisters at 10 inches its going to take a bit of space. now im under the impression you can either hook this to a sink or hardpipe it in from the main water line into your house.. is this correct?
i would prefer off the main line. my mechanical room backs onto my garage these canisters are all sealed so no dust can get it right? i would prefer it in the mech room but its pretty packed in there garage may have to suffice. does this kit include everything needed to pipe to the main water supply? as in the fitting to the unit apart from a Tee and some o rings?
how much waste water does this pump out?

i just want to make sure this is right as 5 stage 75 gpd kits in LFS are clsoe to 400 bucks after tax and i am going to drive across border to go get it..
thanks in advance