It doesn't affect cooldowns if you successfully interupt an ability.
Yup. The strategic way to use it is 1) as an interrupt or 2) when you are up against characters that need to spam abilities. Hit them with deep freeze before they start spamming and cd shoots up. 1 level of it isn't really extremely useful for causing a big amount of pain early game, but if you put several points into it, it can be exceptionally strong.
+1 for hedgie though. Good details.