You can do DB military press if you wish. Just find the proper weight and get the form down. Also, the “pole” is referred to as a barbell, or bar :3.
Not really. Pullups and chin ups help greatly in improving your pullups and chin ups. Deadlifts are mainly a lower back (spinae erector) and butt/hams (glutes) exercise. Chin/pullups are mostly upper back dependent. You’d see more co-dependent gains from barbell rows for chin ups/pullups than you would doing deadlifts. However, you still need to do DLs. And the only way to properly get better at an exercise is to do it, not do something else.
Sounds like a brilliantly stupid idea to me. Sets are not counted by the amount of weight you cannot do. There’s a reason why the system goes (e.g: 135x5x3) like it does. 135 is the amount of weight, 5 is the amount of reps, 3 is the amount of sets, etc. I’ve truthfully never heard of this “method” you mentioned and I cannot see it being useful. If you can’t do the weight, don’t do it.