The bridge is a simple bolt. It yields a bright tone due to the strings resting on metal. The threads allow you to move the strings just where you want them. You can replace the nut bolt with a smaller or larger bolt to raise or lower the strings. The width of the neck is 1.5" so the nut bolt must be 1.5" long.
The strings are looped around the screws in the rear of the guitar to hold them in place. They must be stretched taught in order for the string be tight around the screw so the guitar stays in tune. When replacing the strings, do not remove the screw, simply cut the string off the screw.
The bridge is held in place by two screws in front of it to keep it from moving. This is called a floating bridge. Sometimes the bridge is slanted for better intonation (in tune all the way up the neck).
The jack (guitar cord input) is a typical 1/4" standard guitar jack that you'd find on any electric guitar dating back to the 1940's.
Contrary to popular belief, you don't need a large sound hole on a cigar box guitar. That's because the small body of a CBG projects the sound at a loud volume even with a 1/2" sound hole.
Sometimes I put two sound holes in the front corners or the CBG and sometimes just one in one corner.
The L bracket allows you to raise or lower the strings by tightening or loosening the L bracket screw that is in the neck. Tightening the screws lowers the neck about 1/8" which raises the string, conversely, loosening the screw raises the neck and lowers the string. Experiment to find your favorite string height. Higher string height is recommended for slide playing.
Not much to say about the strap holder :)
The tuners are standard open gear guitar tuners. If you choose to, you can replace them with guitar tuners of your choice.