How to check card balance and maximum amount allowed during recharge

I will be arriving in Shanghai Pudong International Airport and intend to get the card.

1 - At which floor can the card be bought?
2 - Pay deposit of CNY20 to buy a card and recharge the card with some value, minimum of CNY10 and maximum of CNY1000? Will there be any receipt given for the deposit? If yes, must the deposit receipt be shown when I want to get back the deposit and balance refund at the Pudong airport when I depart?

I wish to get to Shanghai city via Maglev so after I topup the card with value, I just proceed to buy the Maglev ticket and pay using the card?

How to check the balance in the card?