Everything's going according to plan. Check out Youtuber Sariel's review on your set HERE.
At about 26mins in, he addresses your concern. He notes the looseness of the feet when fully deployed, and says there are 4 pads stored in a compartment over the front axle. Just build on.
It might be impossible to give the precise number simply because some older sets are yet to be found and new ones are being added with a slight delay.
These three are the major websites having the most details about sets:
Bricklink catalog has 15824 sets in its catalog.
Brickset has 16378 sets.
Rebrickable has 15432 sets.
As you can see numbers are ...