Getting the Courier's Rasher is going to require you to complete two other quests before you can get this item: My Missing Courier and My Missing Brother. You'll also want (probably need, to be honest ...
To find the Watcher, head up to where you found the Memory Locket in the very first vine platforming area, in the southwest ...
To really finish up with everything that Silent Hill f has to offer, you're going to need to complete at least one NG++ (or NG+2) run after NG+.