1) So if we have plane with 3000kg and we must have best L/D and if wingspan is not constrained, then we must choose bell spanload so our new wing will be 22% longer and it will has 11% smaller induced drag?
Induced drag is not all. At high speed friction drag will dominate and at best L/D it will already contribute half of total drag. Those 22% will also add more surface area which adds friction drag. Real designs are a compromise which looks at both components, friction and induced drag.
2) Why Al Bowers talk like airplane overall weight and wing bending moment are same thing?
He simplified things, as did Prandtl in his article which is the source of Al's wisdom. If the mass that counts (the payload) sits in the middle of the wing (i.e. in the fuselage), this simplification is justified. Airplanes need to have practical value and a big payload fraction means more practical value for the operator.
3) Why all gliders use elliptical spanload if bell spanload has better L/D?
Because they need to minimize drag with a given wing span. Given their high aspect ratio, the speed of best L/D is close to the stall speed already, so in most of the speed range friction is the dominant source of drag. By keeping wing area low, this drag contribution is kept low as well. There have even been attempts at reducing wing area in flight (fs-29, SB-11) in order to improve L/D at higher speed.
4) What do you think, when will aircraft industry switch to the bell spanload solution (if ever)?
You may not have noticed but they did move away from the elliptical lift distribution long ago. Only in the times of biplanes a constant chord over span was favored, but as soon as cantilever wings were used, wings became tapered (exceptions apply, of course). But witness the taper ratio of most wings - they would have atrocious stall characteristics if they relied on elliptical loading. Of course they use proportionally less lift near the tips in order to minimize drag.
You can see that the outer contrails of this Boeing 747's engines wrap around the contrails of the inner engines (picture source). This shows how the air is pushed down in the wake of the wing and that the centers of the vortices are slightly inboard of the outer engines. The outer wing contributes little lift; however, this is not an ideal bell-shaped distribution with download at the tips. Again, it is a compromise to minimize overall drag.