There is only one way to become a good shooter and that is to practice using good basic technique. You will need to put up about 700 shots a day. When you have paid your dues in the work sense of the word developing good form the range of the shot will increase.
Four players standing still make every ball handler's job harder. Teach V-cuts, L-cuts and back cuts so your team gets open and punishes defenders who overplay.
Good team defence is five players guarding the ball, not five separate one-on-ones. The shell drill is where that starts, so here is how to teach help-side positioning and rotations from the first week of the season.
Rebounding is the least glamorous thing in basketball and one of the most decisive. It is also almost entirely a habit, which means it is entirely coachable.