I will start with the placement question. Placement is not real critical but it is always best to place the shunt termination as close to the termination point as possible. For your first question; in general practice I have always laid the pads for series and RC shunt terminations and ended up either using a 0 ohm for series with RC or some series R and DNI for the shunt. Only in case with really long ugly lines have I needed both. Adding 0805 pads is cheap, easy, and uses little space. Simpler to plan ahead, and stuff a zero ohm or make a DNI than re-fab the board.