Shoot me email and I'll fix it for you if you like.
I'm not sure about the payment provider but I'm sure there is one you can use. I think 2CHeckout might work for you if you can't get stripe or shopify payments.
To change the logo on the checkout you need to do this
As for the credit card payments I've never used 2checkout just heard they're a option. I normally use Stripe , eway or shopify payments but if they aren't available try 2checkout.
Hope that helped.
I just took a look at your store and I think it looks really good. There are just a few minor things that I might consider changing
I noticed that you don't have social media links. Adding social media accounts for your store can help you better advertise. If you have a lot of followers on your facebook or instagram, it can create some social proof, and help more people buy from you.
After carefully reviewing I don't see a sense of urgency. By using urgency, you can make your visitors feel like they are missing out unless they order immediately. The 'Fear of Missing Out' that they experience, will increase your ability to convert them into buyers. One app that can help you with that is https://apps.shopify.com/better-countdown . It really can make a big difference in getting your customers to buy from you
One thing to consider is adding a blog. If you had a blog you would be able to drive more organic traffic to your store, plus it would help establish yourself as an expert.
Nice job on your all of your hard work so far, and I'm sure that just a few minor changes will really help.
By the way, I created an email course at https://mailchi.mp/7d8692283c12/shopify-conversion-course (I'm not selling anything) that might help you optimize your store.
To learn more visit https://www.answrly.com/