The biggest impact to having a project run on time is picking the right contractor.

This is not a do-it-yourself project.  

We don't have a formal construction background, but are capable of the basic work not involving permits.

Is it important to try and project insurance cost in the next 5-10 years and factor in potential climate risks in the area?

I have personally done brrrr projects and sold a lot of flips there. 

Do you guys prefer to bite the bullet and hire a full General Contractor (GC), or do you step into that Project Manager (PM) role yourself and just manage the subcontractors?

I’m looking for tools or data sources that project insurance costs over time and climate-related risk (areas that may require flood insurance in the future or see outsized premium increases, etc)I know I can get current insurance quotes, but I want to understand historical trends and forward-looking projections so I can better assess hold periods and identify markets to avoid based on rising premiums or climate changes.

Renovations are normally divided up into different projects and each project has its own invoice.

Use that basic number for rehab projects tend to get people into trouble. 

You're going to want to use projects for this.