i believe it is to collect the fuel from when the car is off and to collect gas vapors. i think i've heard people attaching it some how to the top of the gas tank. i don't think if you shorten the lines it would have any affect on the comp.
i also doubt the e-brake would be a problem, unless ur body droppin, there is a pretty good amount of play in the cable to allow for travel. only thing i wonder is if people have problems with the driveshaft if the link is not set up properly. just becareful with the lines, make sure there away from all exhuast and sharpe corners or edges, if there near an edge, get some cheap hosing to wrap around the airline. don't forget to trim the coil pocket, its a good idea to do on all front setups.