You are in a great place to learn based on the successes and failures that many have had.  

For example:CapEx: $250-300 per unit per year for older properties, adjusted based on age and condition.Maintenance: $500-800 per unit per year, depending on property class and tenant turnover.Make-Ready Costs: $1,000-2,000 per unit for turnover, depending on the scope of work required.Resources and Tools: Utilize tools like BiggerPockets’ Pro Calculator or other underwriting spreadsheets that have built-in assumptions for these categories.

Would you recommend the route of a first lien HELOC based on the above situation and information?

An additional benefit of a detailed engineering-based Cost Segregation Study is that it can increase potential insurance premium savings as well as provide support for the property tax appeals process.

@David Cook this is why we’ve started using water based polyurethane on our hard wood floors.

Bathroom:Demo & Prep ($750):DIY toilet, vanity, and flooring removal.Professional plumber for plumbing adjustments.Toilet ($250):Standard, efficient model.Vanity & Sink ($900):A modest-sized vanity and sink combo.Flooring ($500):Wall Tile (Shower/Tub Area) ($1,000):Basic ceramic tile for the shower/tub surround.Shower/Bath Fixtures ($250):Update showerhead and faucet.Lighting & Paint ($250):DIY painting.Update light fixtures.Permits & Contingency ($3,000)Total rehab cost: $30,500Amount Needed: $30,500ROI: 45% of $30,500Investment Duration: 30days Profit: $13,725Total payout in 50days: $44,225EMD: The buyer has put down a 20% earnest money deposit based on the property’s ARV and they are all set to complete the purchase as soon as the rehab is done.To find out more about our Joint Venture projects, please visit our website: http://strandparkproperties.comWe're able to guarantee the return on investment (ROI) by finding buyers for the properties before listing them on our website for possible joint venture fix and flip.

Feel free to reach out, and I can share some recommendations based on your project

Should he be exposed to all liabilities that comes with it such as lawsuit, history of insurance claims(I believe insurance have a data base of past claims that can affect future coverage), credit and what not at an early age? 

Just keep in mind that there are further steps you'll want to keep to minimize the possibility that your entity is ignored for this kind of personal liability (say, if you were the person who didn't properly clear snow, or if your finances and the LLC's are comingled).And I agree with @Chris Seveney, insurance may provide adequate protection based on what's available to you.

I suggest running an analysis and just sharing it here on BP.I am also happy to hop on a call and point you in the right direction based on some of my experiences- no matter what, keep at it...this stuff takes time.If you get a deal here in Chicago and need to partner up, I am your guy!