My big question is when quoting a renovation, since I don't have the experience what is the best way to come up with the right ARV so I can make the right offer.

I would be happy to talk or meet-up to talk about our experience.

I don’t have any experience with investment properties any advise will be highly appreciated Thank you !! 

Does anyone have experience developing residential communities with prefab/modular homes (not mobile homes) or know someone who does?

House hacking will also give you some personal "property management" experience.

We have over 5 years of experience owning and renting long term and recently short term as well.

I.e. roofs cost $6k+ for me, HVAC going out can cost $8k+.Tenant Risk: this is the most realistic one, in my experience.  

I recall Brandon mentioning it's not all about profits, it's also about the learning experience.

As Columbia Market Sales Manager, Chris points out below the iterative journey of change we all experience in high school and as a beginning real estate professional persists even at the highest level of high finance and development.

Given your experience with Travelers are you still with them or have you moved on?