Just received my Arudino Uno starter kit from Amazon (seller Arduino). When attempting to assemble the wooden base I found the directions lacking. There were additional parts and it doesn't specify how to assemble the base only the feet. Since there are wooden parts left over it left me guessing as to where they should be installed like the feet. All wooden parts are labeled yet in the directions there are no references to those labels only an illustration showing the feet being installed. I almost installed the feet upside down on the wrong side of the board too. Having never held an Arduino before these mistakes made assembling something as simple as a wooden base a little frustrating. The lack of direction in the booklet was confusing. Hopefully this will help you to improve upon instructions in future iterations of the packaging. 
The other pieces aren't for the base. Page 12 says at the bottom that the other pieces are for other projects.
Haha I had the same problem! The third instructions shows the Part A legs going into the top of the base, then later it magically shows it on the bottom of the base. 
I made another posts that states other problems with the instructions (like where to find the screws and use the washers).
Good thing it wasn't just me!
I had the same problem just now. Step 3 to step 4 makes no sense. Was trying to figure out for 15 minutes which side of the board to put the legs onto because the pictures are inconsistent. Step 4's picture is correct, Step 3's picture is wrong.