Hello, I have summarize your requirements of Wordpress expert, we have made similar projects like it, I have an 40+ team and 8+ years of experience, come over chat will discuss about more briefly..
- Theme Customization and Development
- Plugin Development and Customization
- Payment Gateway Integration
- Building Theme/Template or site from scratch in WP
- Bootstrap, CSS & jQuery for full responsive UI.
Kind Regards,
Dilip