I probably wont have the shards to get all the Cards that are available, the six different girls.
So I have been trying to figure out which of these are the best to get, and I haven't found any information on them yet.

Honestly, I feel like some of the other items are probably a better investment for me anyhow, like the Reveal Cards, or the SR cards to boost cards I already have level. Assuming I will have 1400 shards before the event ends, what should I be getting?

Also... do you have to trade them in before the event ends, or will it give you a few days to trade in, after the battles have stopped?
Any information is appreciated, thanks.