yes to your 2nd question. Amazon is still the best platform. You can run a shopify + an Amazon shop if time allows.
what kind of products are you selling? I can help if you're interested in clothing, including "made to order, one piece" and "large-scale production"...
Appfreaker app can definitely meet your shop's needs.
We are providing best dropshipping suppliers to UK ,Let visit our Appfreaker it's a dropshipping app that gives you access to our suppliers like Dhgate, Etsy. Target
We also have direct option like "Add to list " , "Edit details" to import products directly to your store with our app .
It allows you to set up suppliers and import products and set cost prices.
Pricing Automation: Pricing automation will be also available were you change the prices of product directly.
Auto Updating Inventory: The app checks suppliers items stock .