@Alina TrigubA Solo 401(k) does not eliminate UBTI generated when the plan engages in a trade or business. 

No contracts and you can transfer your cameras from project to project.Depending on how much coverage you need they have really low monthly plans.

My mom was shopping an estate sale when the owner told her he was planning on selling the property.

I plan to use two of the bedrooms for Airbnb short-term rentals.

Plans for what you're building will be key - it's too vague and open right now for someone to advise you on potential cost. 

Discuss plan with Planning Zoning group.3.  

In the next 5-10 years, I plan to leave my current industry and transition to real estate full-time, so I’m especially interested in how this could impact that goal.Current FinancialsRoth 401(k) Balance: $105KContributions: $79KEarnings: $23.5KSalary: $109KContributing 6% annually ($545/month), with a 100% match for the first 3%Investment Growth Assumption: 8% per yearCurrent Rental Cash Flow (Pure Profit After All Expenses): $7,500/month (9 units)Potential New Property Cash Flow (Pure Profit After All Expenses): $1,300/monthCurrent Real Estate Portfolio Value: $1.4MAfter New Property: $1.7MWithdrawal Breakdown ($60K)Tax-Free Contributions: $45KTaxed Earnings: $13.4KWhy Only $13.4K Is Taxed and PenalizedMy Roth 401(k) balance is made up of:Total Balance: $105KContributions: $79K (75.24% of total)Earnings: $23.5K (22.38% of total)When withdrawing, the money comes out proportionally from contributions and earnings.

I would just make sure to call the city and let them know your plans in full detail to make sure that you can do it.  

I plan to buy a new property in May by putting 5% down and renting out my current home.

I am in contract on a duplex in Grandview where I plan to live in one side and rent out the other.