WordPress Customization for Author's Website

I have an existing live website using a purchased theme. I need an experienced WordPress developer to implement my supplied homepage design without rebuilding the site or changing its core system.

Current scope is English only, although the website ultimately supports English, Persian and Arabic, so all changes must remain multilingual/RTL compatible.

Requirements:

Recreate my supplied design accurately using the existing theme.
Fully responsive desktop/tablet/mobile layout.
Excellent loading speed and clean lightweight implementation. Fast pages are important for usability and performance.
Work on staging/backup first: no downtime or disruption to the live website.
SEO-friendly implementation: semantic headings, descriptive image filenames, ALT text, optimized image dimensions/compression and clean page structure.
Preserve existing functionality, URLs and multilingual architecture.
Cross-browser testing.
No unnecessary plugins or bloated page-builder code.
Provide a final tested page before deployment.

To apply, please answer these 4 questions:

How many days will you need?
Can you work safely on staging without downtime?
Show 2 similar WordPress/theme-customization projects.
What performance checks will you perform?

Start your proposal with “M2M” so I know you read the complete brief.