Beginner questions

Hi everyone! I just began playing today and I really enjoy it so far.

My favourite character is Elsa and in wondering, is there a way to get her besides saving up the blue coins? Also, what is the difference between purple character shards and yellow ones? I am a bit confused on the currencies and how to level up to new characters, to be honest.

My name is princess.grace if anyone wants to become friends! Thank you!