I'm thinking of using woocommerce on my WordPress site to set up a small online store that will accept credit cards on shared hosting, but I'm confused about what's needed, ie, the Mijireh Checkout comes with it, a payment gateway and a merchant account with my bank. Is this correct? I understand what each does, but does Mijireh not act as a payment gateway or do I need both? What's the difference between a checkout and a payment gateway? Thanks.