So anyone who's experienced in this field, please help with these questions

1. Guest wants to pay with 2 different cards. Example, total is $70, and she wants to pay $50 with one card, and $20 with other. How do I do this?

2. Guest give the right amount of money for payment, but I enter it wrong. Example, total $100, and I enter $200. How can I correct this after the receipt printed out.

3. By accident, I close the thing contains the money ( i don't know what it's called) before I put the money in, how can i re-open it?

Thank you so much in advance.