Could I claim it as my own but won’t actually own it until I am 18?

I grew up in Hoover, and in medical school I lived in the Crestwood area downtown and I was drawn to that area if I decide to invest there. 

If you are reasonably certain that the son has inherited the property, and you are content to rent the property for cash flow, then go ahead and offer the son $10k for signing his interest over to you via a "Quit Claim Deed'. 

They claim to lease the property for a period of time, take care of all repairs under $500, and utilize a lease option to purchase the property within 5 years. 

(That would appear to cause a double claim of the expenses)Finally, regarding the $30,000 in improvements.

Can a landlord say he didn’t receive rent for August and September in the middle of Jan

I think I'd prefer to have higher stated expenses from the seller, rather than a seller claiming to only have 20% expenses per year, as it just adds more upside to the deal if you know what you're doing.

I would even check insurance claims made on this property, ask for a CLUE report. 

This is because the state income tax will already bring them to $10,000.They may get a benefit at the state level for the property taxes.A discussion should be made what type of house they would buy and if they would have any itemized deductions(Medical or charity) besides the mortgage interest and Income/Property taxes.Otherwise, if the itemized deduction is marginally higher than the standard deduction, it wasn't the best tax write-off. 

Finally if you don't get anywhere you could bring it to small claims court.Good luck!