they can be used for black and gray water...but usually folks only use them for 'gray water'. the black water tank can last much longer especially if your campers use the park 'facilities', i.e...bathhouses.

Yes, it comes with it's own hose.

regardless the size, you should not tow your tank far, or very fast! A speed no greater than a fast walk would be max. The wheels on these tanks aren't made for road travel...just to get you to the campground d/s. S-L-O-W is the answer.