Second pic is to hold your chain when you remove/replace the wheel. I had to ask the same question here on BF quite a few years ago.
You probably do need a guide on the bottom of the BB. Some bikes from vintage days just wrapped the bare cable around the steel BB shell and made notches to keep it in place or had little bend pieces of metal to run the bare cable through.
On my bike that I also learned what that chain peg was for, it also just wrapped bare cable around the BB. However after a few thousand miles, I started having some issues shifting and it took some time for me to discover that the cables were sawing into the BB. One of them almost cut completely through. So then I spent the big bucks to get this Shimano BB guide and drilled a hole for the scew where I felt it belonged and ground off the pieces of bent steel they'd brazed on it.
https://www.jensonusa.com/Shimano-SP...RoCRhYQAvD_BwE
$3.00