Expence tracking without a Business?

[Gleb Dmitriyenko]

Hello,

I purchased my first house hack in Sacramento, CA recently, and I have some questions about tracking expenses.

What do I need to have to have in order to write off expenses as I am prepping the property for renters, adding features, and getting renters in?

I've been tracking all of my expenses using excel and Stessa which I really like. I do not have a registered business, and the property is considered my primary since I will be house hacking it. I know I am all over the place, but my main concerns are as follows:

1. Do I need to create and register a business with the government and if so what kind do I need for tax purposes/me needs?

2. I've been using capital from my W2 to fund the work on the property, can that apply to business expenses?

3. I do not at this time have "proof" that rooms will be rented out to tenants. Does that affect my strategy for tax planning?