Cantilever not returning could be spring tension, corrosion, broken pieces/mis-placed spring, or the dreaded post bulge from over-tightening the mounting bolt.
Locking the rear wheel is not a sign of a well adjusted brake. Sure it gives the impression of lots of power but usually this is the result of a mis-matched lever to brake system. You want a brake you can hammer on and slow you down fast. Remember locking the wheel is not an effective way to stop though it is satisfying to be able to do it. A brake should have good modulation and you should be able to have a range of effective braking as you pull the lever in. If the throw is short and the brake locks quickly, that is a poorly adjusted brake.
Hangers are pure fashion. The original mafac/dia-compe ones work just fine. The shimano safety ones also work great when paired with the right cantilever and make adjustment straight forward.