Shopify credit card processing for merchant transactions

Retail & Point of Sale
1

We have a custom screen printing business and process credit card transactions and we want to set up a Shopify store and offer custom printed items. We want to use Shopify’s credit card processing but don’t want to maintain two credit card processing providers. Can we use Shopify’s processing for our existing brick and mortar business or is it a hassle?

Thank you in advance.

2

I dont think you can without paying the fee for the Point of sale app. I am in a different scenario; I want to keep/use my current credit card processor for a second location instead of shopify payments because our current rates are at least 1 % lower. However for the seemless checkout I think you have to use their payment processing(2.5% for in person)