1. Your nitro groups have gone crazy. I assume this is a SMILES typo - use N(=O)=O, not N=O=O.
2. Look up the regioselectivity of permanganate oxidation of aromatic hydrocarbons.
3. So you are suggesting Na2S reduces an acid to a hydrated aldehyde. You are on the right track with reduction, but it won't reduce the carboxylic acid - something else...
4. It looks like you have identified this as diazonium chemistry - but, have you ever seen the formation of diazonium salts from nitroarenes? What functional group normally forms a diazonium with HNO2? This gives you a big clue about step 3.