Hearty Welcome to the Candy Friends section of our friendly King Community
To answer your first Question -- TO earn the costume, you will have to earn certain number of Stars. In simple words, it is another "Star Chaser" event. For iOS devices, it was available from 12th and Android users it will appear tomorrow (15th).
Here is screenshot from my game to show you how the event looks
And with regards to your 2nd Question about the "Piggy Bank", you have the option of buying it for the discounted price like in the pic @marscrushinit shared OR you can just ignore it and don't buy it at all. It is completely up to you to spend some real money in your game(s).
Hope this made sense! If you need any other information, please do post back
All the Best & keep having fun with crushing the candies