Hi, I am seeking advice on what kind of entity I should form for tax lien investing. 

If you are setting aside funds for capex, taxes, insurance, or other expenses that don't occur monthly, transfer those funds to Savings each month and hold them there until it's time to spend them.

We as a firm have investors working with us who have rental properties all over the US big and small.Finding a real estate-focused tax professional and one who can help with advisory and grow with you would be my suggestion to focus your efforts on finding.

You haven't talked about taxes yet.

Property taxes here around around $10k/yr so around $800/month.

Instead, the activity is reported on the individual members' tax returns.You can still claim depreciation on the property on your Schedule E.

Even adding yourself as additional insured does.Making a claim as additional insured may cause you to be unable to recover anything.

So far, I am in the midst of purchasing a couple of mortgages and I have purchased tax liens and deeds. 

It was a leak, fix it replace the sheetrock and damage other items and move on Why would you file and insurance claim for such a small issue?

I am also including the taxes and insurance while running the numbers.