Shopify Website Bug Fixes & Optimizations

My Shopify website needs some urgent attention. I am facing broken links and mobile responsiveness problems. I also need to integrate some product page optimizations such as improving load times, adding a page footer, size charts, and a sticky 'Add to Cart' button.

Ideal Skills:
- Expertise in Shopify
- Web Development
- Problem-Solving

Experience in optimizing product pages and fixing bugs is preferred. Please reach out if you can help.