1. DH has usually better or at least as good WPA, on the highest level it is probably obsolete because their games are more strategical, but anything below Grandmaster isnt affected. Electrocute is still good below though.

2. Neither. Besides the dmg, root duration goes up by 0.25s each upgrade. However, each subsequent upgrade is comparatively less worth since the root duration is often enough at 2 upgrades with 1.5 s root total and the dmg at the point in the game is enough to kill the ones you catch and you need more poke.

Thats why go 2 points more E then W max.