Not sure about the Edelweiss skill, but I'll keep an eye out for it.

1. Tap them with a squad of only a single 2-star unit so that as many people can hit them as possible. Unless it was changed again, their timer is super long and the rewards are excellent, so sharing them with a lot of people is best if possible.

2. The spinning arrows are random. The blue arrows switch to the next position each time a team passes over one.

3. Yes, just save them up or roll one of the other premium gachas (Limited 2 or Premium). You can check what is in each of them and decide if you want to roll. Also while it was inefficient to roll like that, you got a 6-star so whatever (jealous )

4. It's cheaper to use them on lower level girls, but the amount of exp they give is the same so it's up to you. Usually after 40 is when feeding gets really expensive, and a lot of people stop feeding level 5 manyus and switch to level 20 manyus as early as 30.

5. Yes

6. Don't do the dragon dailys if you don't need them to evolve stuff (unless you need to inefficiently burn stamina before leveling and have nothing better to spend them on). Early on I was just running all the stages I saw to get 3 medals on, but I ended up wasting a bunch of stamina running dragon dailys when I was new and ended up just selling everything because it was clogging my inventory. You'll eventually get 3 medals on them so there's no need to rush.