How can I estimate the initial repair costs?

If thats the goal, then it makes sense to do a series LLC, there's nothing wrong with initial formation as Series..

(Looking for SFH or duplex for under $100k, with under $30k in rehab needs)We plan to take out a HELOC for the down payment and initial rehab costs.

Try call garbage company and verify.

Even though initially I would have said 5 years, I can go ahead with financing prior to that then?

Also if you are not going to scale up, it doesnt make sense to be an OOS landlordwhen I thought I wanted to be king of the C class rental world and bought 350 of these.. one thing I did prophylactically was I replaced the waste line on all our homes during initial rehab

Ripoff Report verified them! 

to provide an update (I had it for awhile just forgot to provide it), the title search came back way too out of hand where there wasn't any room to work around it... verified it with my title search person and closing agent, it was not doable. 

Without further ado, here are the final details:Purchase price in 2018 - $210,000Sales price in April 2022 - $450,000 (cash, no inspection, no contingencies)Net proceeds - $249,000With initial out-of-pocket investment of $27,000, the return is a 9.2x multiple, or 84% IRR, which is by far the best real estate investment we've ever made, and gives our daughter a great start on her financial life.

Most appraisers will take into account both your actual rents (as verified by 2 years of tax returns) as well as what they consider market rents.