The stop is also designed if you are using the saw to make a plunge cut where the risk of kick back is greater. Used in front of the saw it can be a limited stop for either the saw or a router.
If you do perform plunge cuts, I would advise clamps of some type to hold the rail to the workpiece.
Do you have bevel locking knobs on both the front and rear of your saw? The extra knob and bolt etc looks like it could be one of those.
There aren't any dumb questions [big grin].
PS: you might want to download and print the supplemental manual fo the saw. It has a lot of useful information. Here is the link:
TS 55 Supplemental Manual
Peter