on the bearing test. grab the top of the tire and pull out/in. it should not move at all. if it does, you need to investigate further to determine if its the ball joints or the wheel bearings.
for a u-joint test, locate the axle u-joint and hold both halves and twist them back and forth against each other. if there is any movement, its bad. if there is any movement, and its dry, it'll make a click or clack sound. this test might be easier on the ground, where the wheel will remain stationary while you twist the axle half.
neither the bearing nor the u-joint will cause the seal to leak. it only leaks because of a bad seal.
a front end rebuild is a lot of work, but if you take it all apart one time and replace the cad bushings, seals, u-joints, bearings, and brakes. also check/fix any collar or cad splines at the same time, then you'll likely never have to do it again.