At 18, I would get a CC and use is sparingly.

One option is to use a smart lock for the deadbolt and a non-locking handle, and then keep a spare key in a lockbox outside so you can let someone in remotely if the smart lock fails for some reason. 

Those are expensive and hard to find, so the next option is a big house with 5+ bedrooms where you can rent out the spare rooms.

I would get leads sparingly.

To avoid her trying to use it as spare income on my behalf, I thought that I could create an operating agreement that states 30% of the revenue must be set aside each month for Cap/Exp/Vac. 

I've been reading every day in my spare time to understand the process of what I'm getting into.

After listening to the Biggerpockets Podcasts, Real Estate Rookie podcasts, and reading more books in my spare time, I have found a niche that I want to learn more about; Multifamily Homes.

This will give your lender more comfort... and perhaps spare you from having to put more money down.

I will be financing $210k of the new condo and plan on putting all of the rental income I can spare from my current rental towards the principal for the next few years.

I have a spare bedroom in my house and I was able to quickly find a person interested in the bedroom.