Sitecore Code Revamp Project (changing get by Item Path to get by ID or better approach)

We have Sitecore websites (1 big, 3 small) that was built fully, but we have a problem when changing item location under the content tree we can't because most of the code is calling items by Get Item Path and not dynamically. Our Requirement>> The sites are fully designed and functional, and we have the code, what we need to Sitecore expert to find best and least-risky solution to enable dynamically reading Sitecore items to avoid breakage when items are moved around in the content tree. Hiring Criteria: Successful candidate to demonstrate capability & approach to fixing this (this is sensitive project, we don't want experimentation) and provide rough estimate in terms of hours needed. Kindly answer the below questions when submitting your proposal: 1- Do you have experience in revamping sitecore code to make it dynamic? 2- What's the most complex project in Sitecore which you worked on (technical challenge), and how did you successfully deliver it?