We often import hand renderings into Revit projects for plotting presentation sets.
I've noticed that when I import an image directly onto a sheet that if the image is even slightly outside of the scope of the titleblock then plots can come out centered incorrectly. The only solution is to place images in a drafting view (or legend view) first... then place the view on your sheet. If the view itself is outside of the scope of the titleblock Revit will plot the sheet fine.
Rescaling the image can also be easier from a drafting view once scale is established. Just change the scale of the view. Rescaling the image by eye on a sheet is less accurate.
Legend views can be placed on multiple sheets but placing these images in a legend view can crowd your project browser so I would stick to drafting views unless you absolutely need the added function of placing the image on multiple sheets like for key plans as an example.
If your image comes in solid black it's most likely a memory issue. You can change the resolution and image size to reduce file size if necessary. Rotating images can also cause them to turn solid black.
Images can be imported. Linking an image for easier updating is on the wishlist but is not yet an option.
Feel free to comment on the subject of importing images if you have anything you want to add.