WordPress coding/problem solving

I'm looking for an experienced WordPress developer to create a blog site.

Essential requirements:
- Match old wordpress theme to be compatible with latest php version
- Diagnose and advise possible changes
- Help solve theme is unable to match up to latest plugins which causes downtime to website
- Be active and update whenever possible. Do not go missing and provides no real time updates

Ideal skills and experience:
- Proven WordPress development experience.
- Strong problem skills.

Please provide samples of previous work and a timeline for project completion.