In order to make a test payment, you can use the credit card number 4242424242424242, card's expiration date must be a date in future and card's CCV could be any 3-digits number (for example 123).

Products module can show deals in vertical (on the right side) or horizontal layout (at the bottom).

You can add a buy button of a specific product directly to an article or a Custom HTML module.

Buy

 

You can also show a re-order button as well.

Click Here to Re-Order