i'm installing a half bath...toilet & vanity....the vanity will be 1-1/4" to a 1-1/2' waste line...vented to the soil line vent.....can the toilet be a 3" flange/line to a 3" soil line and a 3" vent line....or is the toilet always a 4" flange and line........can the vent be 2"..... also a...