1. Katie will always be worth it, she is a very solid addition to the team and brings you more unit points. After her i'd say Iris, Cloris and Leanne are very good contenders. Most of us use CC so you'll just have to deal with it

2. Keep him for male only missions. Early CC'd or not he will still be a decent unit for those since you do not need the most highest leveled units ever. If not, keep him to CC other units with. We don't really respond harshly to stupidity, only stupid people that are unwilling to learn from their mistakes :P

3. It really depends. I'd say at least one CC'd mage is needed with two more fairly high level ones and a decent leveled witch. Along with that, Katie you'll want CC'd and perhaps a healer and Leanne. I suggest searching for the mission on youtube, there's several different guides on how to take it down which can give you a hint of required unit levels.

4. It really depends on whether you truly must have that stamp card. I mean, the units you can get from your first premium could make a big difference, but there's also a chance that you get crap stuff. Purely by stamp card "efficiency" it is indeed better to wait to february though.

5. Horo/Holo from the anime Spice and Wolf.