Maintain proper records - Contracts, Settlement Statements, Agreements, Promissory Notes etc.Additionally, you can track income and expenses consistently, using software or spreadsheets. 

Here is a great example why.I recently saw this asset come across my desk which was a non performing loan where the seller was a year behind (they made one payment I believe - even though they were allegedly properly underwritten).

The potential tax implications are often minimal, and with proper planning, you can maximize the benefits of your investment while minimizing any tax burden.

However, split systems are like large lego sets and the biggest margin for error with this system is reliant on a properly installed system.

Challenges like unexpected renovation costs and tenant turnover can arise but with proper preparation and management, you can achieve great returns.

For newly constructed, purchased or renovated properties and also retroactive generally over the last 10 years, building components are properly classified into individual units of property and accurate recovery periods for computing depreciation deductions.

Where can I find proper leads or wholesalers?

When using this structure for investments, the key is to complete IRS Form W9 properly.

It was very complicated and cumbersome to set up properly and difficult to use.

The answer sort of varies on a few factors like are you self-managing, have you had a proper conversation with them over the phone, etc...