advice and this is urgent!!

Hi,

I am new here.

there is a house 85 old which close to PHL Chinatown .... asking for 90K. A lot of mexicans around. I am thinking to invest it as monthly rent will be around 800. But, when i checked the house, i noticed that the first floor is not flat and there is a hole at the edge of the wall. The seller is telling me it is normal as house is very old. I have following questions:

1) Seller is suggesting to put less value in the contract as she wanted to avoid to pay tax, can i allow her do that? 

2) Seller is telling me that she already found mexican ternants and showed me contract. I am not sure if that is true or not and i dont have experience to find tenants as i am living far awaay from Chinatown.

Any suggestions on if i should buy this property?

Thanks in advance.