What a shame! Since you got it for free and it is so badly soiled and smells bad I would go ahead and try running it through the washing machine. Put it in a net laundry bag, or tie it up in a pillow case when you wash it. I have used Woolite to successfully machine wash leather goods, but you might consider buying Leather Therapy's leather laundry products. They come in 4 oz, 20 oz, and 1 gallon sizes. Below is a link for the 4 oz set.
I would not put it in the dryer. Stuff it with clean rags or old towels and let it air dry while sitting on a towel. Turn it and change position during the drying. You can apply conditioner lightly during the drying process to slow it down and reduce spotting. But use the conditioner lightly, you don't want any stains bleeding through to that beautiful striped lining.
After a day or so, remove the towels, maintain the desired shape, but pull the lining out a far as you can so that it will dry. Again turn it and consider a light application of conditioner during drying.
After it dries, if there is some spottiness or unevenness of color, using Blackrock's Leather n Rich cream and then buffing it with a brush or soft cloth usually helps even out the color.
I would be careful about trying to polish the hardware. The 65th legacy bags are supposed to have dull-looking "antique" hardware. You may not like it at first but you can get used to it. I did!
You might just try rubbing it vigorously with a dry jewelers cloth to burnish it a bit. I once had to polish the hardware on a small legacy wristlet because it was badly scratched and I had no choice. It was a lot of work and I needed to use a dremel power tool to get rid of the scratches. It came out bright and shiny but that's not the natural look for this line of products.
There's a lot of hardware on that Leigh bag and I would leave it alone as much as possible unless it has verdigris or some other serious condition issues. Good luck!
http://www.amazon.com/Leather-Thera...75583&sr=8-3&keywords=leather+therapy+laundry