Shopify Store and e-commerce website Redesign Requirements

I need help with: 1. Redesign the existing Shopify store to include API integrations 2. Redesign existing Shopify e-commerce website(cosmetics) to ensure proper Store customization, Payment processing, ready for marketing (SEO, etc) and integrate with social media update Inventory management: an update shipping mgmt on Shopify. Goal: to have a very professional e-commerce website resulting in high conversion rate