You're right! It looks like the Added Damage effectiveness was not applying to the base Cold Damage per Intelligence. We'll get that fixed and are also looking at adjusting the damage per Intelligence from Icestorm. Upwards, not downwards.
Any clarification on Orb of Storms? Manifesto (and Patch Notes) mention a duration, but the patch notes included a line that says it no longer has a duration and instead lasts for a specific number of hits.
At level 20, Orb of Storms will disappear after 29 strikes.