1) Overwhelmed is usually negative, so they`re saying they have what people would consider to be too many things to do but they`re enjoying it or it at least is good for them. `Fully knowable person with unlimited potential` seems like bad writing, maybe they were trying to make the character sound smart. `Person with unlimited potential` means they are a person who has the ability/capacity to do whatever they want, 'Fully knowable person' on the other hand seems like nonsense, something is fully knowable if it can all be known, like 'the cause of the accident is fully knowable' (fully is unnecessary hear though) means that it can be figured out what the cause of the accident is. But you wouldn't say 'the accident has a fully knowable cause'. And people aren't really knowable, an aspect of a person can be knowable but saying a person is knowable doesn't have a real meaning. 2) Uncrumple is a word, uncrush isn't technically but people would get what you mean, though if they laugh understand it's that they think the situation is funny and aren't making fun of your english. 3) I'd say "Voting through a kind of app" but need more context to say definitely. "Voting through kind of an app" could be correct if what you mean is that it isn't really an app.

Usually when someone says they're "overwhelmed" its a bad thing. It means they have more responsibilities than they can handle. The person said "no, in a good way" to let the person they're talking to know its not a negative/bad thing, but a positive/good thing. Thats not something I'm sure I have an answer to honestly. And I would need to see what kind of dialogue came before or after the last question, to know which way is best to say it.