Picking and choosing from other mazhabs

Q: Can a shaafi follower follow hanafi fiqh in matters of tahaarah and purity and perform salah, fasting and hajj according to shaafi fiqh when he feels hanafi fiqh is easier in tahaarah matters than shaafi fiqh? Or can a shaafi follower adopt some opinions of the hanafi Imam in matters of tahaarah not as a whole because he feels it easier? Will he be sinning by doing like this when his intention is not to follow his nafs but to make his life easier? Allah Ta'ala and our Rasul (Sallallahu Alayhi Wasallam) also teach that we should make our deen easy to follow?

Ordering online

Q: The other day, I ordered a pizza online, and paid with my mother's visa debit card. My mother allowed me to use it. I didn't have enough money in my own visa debt card to pay for it online, so I asked her for hers, but gave her the money back in cash on the same day. The day after I was on the pizza company's website, and I learnt that when one orders online, they have to have the owner of the payment card present when the pizza is delivered. They then must show their own payment card as proof as the below term states (taken from their website): "The owner of the card used for payment must present this card on receiving the order. Card payments are secure". I didn't know I had to do this until it was too late, and the transaction was complete. When the pizza arrived, all the delivery driver said was "you ordered online" for which I replied, "yes".  I thanked him, and that was that.  He didn't ask me for proof of payment. So I paid for the pizza, and it came to the right address, and I confirmed that I ordered online when I was asked by the driver. The only thing I didn't know, was that one must show payment card upon delivery of the item. Our beloved Prophet (Sallallahu Alayhi Wasallam) taught us to honour conditions, so that is why I am concerned here. In this situation, what is required of me? Was this transaction still valid?