However, eviction must be by cause (i.e. you can never evict without a justifiable reason - so more or less you are stuck with a tenant unless they stop paying rent or breach their lease, or some other narrow units such as moving in or curing code violations - though then you have to pay relocation costs).

With the future being so uncertain I realized there was a need to do more than just rely on my job for financial security. 

It saved me when things got real (hello, crazy boyfriend with trust issues).Security Deposit: Non-NegotiableOne full month of rent as a security deposit (at the very least!)

Which one is more appealing - continuing to own the house or the security of that much cash/liquidity?

If you have that experience, you probably don't need much marketing, as sellers will be reaching out to you directly.Focus on securing one listing at a time and building momentum.

I know that the general guidance is that emergency funds aren't to be invested, but given our financial security and the fact that we already have a personal e-fund in a safe, non-volatile location, would it still be crazy/unwise to invest this 15k in an S&P500 index fund in a brokerage? 

Quote from @Keilon Morton: I am looking to secure my first tax sale and need another investor to go in on the deal.

2.Are there strategies to reduce the required down payment or secure better mortgage terms?

Assuming plans are needed to secure a permit.

Quote from @Matt Meier: Good morning,I’ve come across a renovation property available at a significant discount and would like to secure it without going the traditional 6-month financing route.