Thanks for the help everyone! I really appreciate it.
1. Which amulets are good for those festivals? They say pick the ones that have the voltage up, but still which ones should I be getting?
2. Okay, after week 13, I got an event after the evening conversation where you go to the store and you see Chihaya. How do you get those After Communication events? I really want to see those other After Communication events that Chihaya is in.
3. During that same After Communication event, I picked the choices the guide told me to pick, but I didn't get any increase in the memory level. In fact, I didn't get a message that tells me whether I got a Perfect Communication or a normal communication.
1. The best choice would be the Mushaharu's Secret Charm. There are several catches to getting this one though:
a) You only get the opportunity to buy it once in a playthrough. The only chance to buy it is after winning the area festival in the capital region.
b) Winning the festival in the capital region requires you to unlock said festival by accumulating 100k fans and bringing a song to the top 20. Even after unlocking it, it is the second hardest festival in the game (after the Vesperia festival, which you shouldn't even attempt to beat if you don't know exactely what your are doing. I devoted a full playthrough to beat that festival). It's on the same level as the Kansai area festival, which is the hardest of the award festivals.
c) It's also quite expensive. Make sure you have 50k to spare when you beat the festival.
All that said, i managed to get the charm during my first playthrough, so it might be hard, but it's possible.
An alternative which is much easier to get (and preferred by some people over Mushaharu's Secret Charm) is Sugamo-chan's Amulet. You get it in Tokyo. You can also try to use it to get Mushaharu's
2./3. The Non-Story-Related After Communications seem to be entirely random and can occur with any idol of your unit. The Story Related ones appear at given dates and only for your lead idol. You can look
here when the story related ones show up. Only the Story Related ones increase your memory level. The others might have some influence on your unit status, but i'm not sure about that.