Probably they are about seven and a half feet long to where the heel chain fastens to the end. So, yes, they are shorter. You can put the hook either up or down. I prefer to have mine up, but it works well either way. By doing that the harness is all open on the top and is cooler as well as lighter weight to throw on and off each day.
Horses tend to sweat under the back band.
If you're just ground skidding and not doing much tongue work, you don't need the back band to carry the tongue weight. It puts most of the tongue weight on the back band and not on the top of the neck. Please be patient with my ignorance, I've never seen a harness like this. All the rest was familiar and helpful. Looking forward to your answer.