And if that's the case my real ROI is 7%.My idea is, I could sell the property and invest somewhere else the capital and get more than 7% (stocks for example, I know it's a different risk, just doing the exercise), or am doing the math incorrectly?

Then the unit typically needs a rehab because rent controlled units typically have bare minimum in terms of tenant enhancements. 

I have been looking to attend real estate / Investment seminars to enhance my knowledge and to keep me motivated, but could not get any link.

If you don't perform under the terms of the contract, Seller can exercise remedies as outlined in the contract. 

A contract could exercise one or both or neither of these, and both operate independently of each other.I told you the Devil was in the details.

I am trying to enhance curb appeal without completely replacing the roof.

Especially if you aren’t sold on the area and may want to not exercise your option to purchase.

And that is in an environment that is more open than what you are looking at.Another exercise to try - buy a half dozen traffic cones, the taller ones that are 20" high or more or pound some stakes in the ground. 

@John HyunFor CA investors you can create a LLC BUT California will exercise a hefty franchise tax of $800 per year. 

You did all the right things, but maybe you want to try the exercise with a lower cost/price ratio.