1) Ucraft is already integrated with Stripe. With Pro and higher plans you can easily accept Stripe payments.
To set it up follow these steps:
1. Enter your eCommerce App System →Payment page and choose Stripe from the list.
2. Click Connect with Stripe button to proceed to the next step.
3. You will be redirected to another window with a Stripe registration form. If you're new to Stripe you should fill in the registration form and provide some details about your business. Click "Authorize access to this account" button to allow your Ucraft store to connect to your Stripe account.
2) As for quickebooks, feel free to make use of Custom HTML Element.
You just need to find a website that provides relevant HTML codes, add a Custom HTML Element from the Elements section and input the code there.
But please note, the code will go active once you connect a custom domain to your website.