Boat detail help please!

I'm detailing a used boat a customer bought. I'm having difficulty with few things:

1. Metal/steel rails have want seem to be "salt oxidation" or something. It's bumpy in texture and is black. I tried heavy acids and fine steel wool but nothing seems to work. Is there anything that we can use?
2. We used regular "car" wax to wax the outside. It didn't really shine up that much. Would using a "marine" wax be better?
3. Boat has couple of white leather seats that has some moldy spots. I couldn't get it out. Is re-dyeing the only option?

If the boat is of any quality, those rails are Stainless Steel that was Electro polished when new, The acid probably destroyed any polishing that was left, as for Steel Wool NO WAY. you are imbedding iron into the Stainless that will leach for years. Been there done that. Use only Stainless Steel rated polish and BRONZE WOOL.
The texture is probably corrosion, the seats probably have been weathered to the point of no return, Dyeing might work .
Gelcoat finish's dont wax up to good if they are old and oxidized, compound first with the proper grit and color. DONT use a red compound on an old white boat. YOU wil get a pink boat for sure.
You are finding out the fact that BOATS are not cars, they dont polish up as easy. Good luck