It's a lot easier  logistics wise and the realtor will also probably have better communication with them since it probably wouldn't be their first deal together

I am logging in mine on a simple excel but am curious how others are doing it / staying organized.

Just for simple math use average 20% personal tax rate.  

Setting up an LLC and accessing 50k+ in business credit is a simple process that protects your personal finances and positions you to scale faster.

I would keep and organize all of your communication around this issue, including gathering pictures of the unit and the area in question that was repaired.

In our area we do not have slabs so replacing pipe in a crawl is pretty easy.. and for sure just digging up water line in the yard is super simple

A certified letter is good because they sign for it, acknowledging receipt, any other forms of written communication you can get to document that they were notified of the hazard probably also helps. 

I have literally shared the communication between myself, seller, and your Realtor/Mom.

In the end, I set myself of up a C-Corp > LP > LLC structure after hearing a lot of people were doing simple LLCs and getting double taxed. 

An FHA loan with 3.5% down could make house hacking feasible, especially if you find a property where rental income offsets much of the mortgage.For now, prioritize house hacking close to work to keep things simple.