Are you satisfied with the progress of the ChampUp team? You guys still have some work ahead of you to get all champions in line with the current gameplay design / balance philosophy. How long do you guys discuss changes in general until you settle for one?

Extremely! I think we've shipped something like... 50+ updates over 2.5 years? That's a pretty massive chunk, and it isn't even a complete picture. We don't always hit the mark perfectly, but we're getting better all the time.
We have a massive amount of work ahead of us still. I don't think we'll ever catch up, and I don't think that's a bad thing. Kha'zix was the bar of "HOLY SHIT NOTHING CAN LOOK BETTER THAN THIS", and that was two years ago. How does he look this year? How does he look in two more years? The thought is pretty cool to me, because hopefully we're constantly making people enjoy their champion more. (We're not perfect, but hopefully you feel we hit the mark more often than not.)
As for how long a particular character takes? Depends on a few things, namely scope, and how quickly we find a solution we're satisfied with. Sion took something crazy like 500 days (not straight or only on him, obviously). It's generally not about when we want to get it out as much as when its ready. Though, that's for the Pre-Production (Concept and Kit). Production is a bit more time boxed, because then it's more about execution than purely idea generation.