Even a contractor with 30+ years of experience only knows what they know - so, they may not know the most cost-effective solution:(5) Political trends that may lead to more controls on landlords - being forced to accept S8, not being able to deny for evictions, rent control, etc.

What is the most cost effective route to take?

If they won't clean it up, talk to the City and see if they have any tools that may help.

This will allow you to run specific underwriting and projection tools to better assess each option.Remember, owning a property with a pool comes with added expenses, such as heating, emergency and routine maintenance, and higher insurance costs.

Ya'll if you are trying to do a deal where you need a lender for an earnest money deposit, you're a tool who's got no business putting somebody's property under contract.

Is there any online services/tools where I can do the above DIY?

I do advocate for mixing SEO w/ a strong offline strategy because they work together so effectively.  

They provide all the tools you need, with weekly calls, one on ones, a private FB group with open communication 24/7, team connections, and accountability partners.

Taking 'effective' action is what you need to do next, find out what your goal really is and work backwards in discovering what you need to do to achieve it.

BP has various tools to help you analyze your deals (rentals, flips, wholesale, etc). : https://www.biggerpockets.com/investment-calculators7.