Upload & Sell: On
In addition to Scott's very helpful comments re BW, since you have CS5, and I assume neither LR nor SilverEfexPro, you can achieve the same results many ways. I think the most direct is to edit/convert in Adobe Capture Raw (same engine as LR without the nice UI and content management tools). There are a number of extensive tutorials on YouTube (search for ACR BW conversion of something similar).
In Bridge, assuming the image is a jpg, rt-click on the thumbnail and select open in ACR. If a raw image, by default it should be opened in ACR with a simple click. All of the essential tools are there in ACR sans the niceties of SEPro re presets etc. plus the process is non-destructive wrt the underlying image.
As for resizing, I use the File->Save for Web & Other Device selection from the CS5 top menu. You will see options for resizing ( 800 on the long side is good, 1024 if you prefer), quality, etc. - not a whole lot of decisions necessary. The result is a jpg. Like you I often generated a mess until I discovered this selection.