What image formats are suitable for printing?
We recommend JPEG images because this format doesn’t allow transparency, which can be a problem in the printing process. Be sure to save your JPEG images with minimal compression/maximum quality. If you’re a Mac user, you can save the images as PDF or EPS. If you use PowerPoint for Windows, you can save the images as EMF.
What image resolution should I use?
The image resolution you should use depends on the type of image that you are using. For colour or grayscale images, a resolution of 300 dpi is recommended, while black-and-white bitmap images need at least 600 dpi. Calculate the resolution of your images – see image.
While your computer screen will display low resolution images well, when printed they will look rough, blurry and jagged. For best printing results, a resolution of at least 300 dpi is recommend. Files with resolution lower than 300 dpi can be printed, but the results may be unsatisfactory.
Ex. if you want your cover image to cover the whole front page of your cover (165mm x 242mm), then the image size should be 171mm x 248mm and 300 dpi.
What is Bleed?
In printing, bleed is printing that goes beyond the edge of where the sheet will be trimmed. In other words, the bleed is the area to be trimmed off. The bleed is the part on the side of a document that gives the printer a small amount of space to account for natural movement of the paper during guillotining, and design inconsistencies. Artwork and background colors often extend into the bleed area. After trimming, the bleed ensures that no unprinted edges occur in the final trimmed document. See image
It is very difficult to print exactly to the edge of a sheet of paper/card, so to achieve this, it is necessary to print a slightly larger area than is needed and then trim the paper/card down to the required finished size. Images, background images and fills which are intended to extend to the edge of the page must be extended beyond the trim line to give a bleed.
Bleeds in the US generally are 1/8 of an inch from where the cut is to be made. Bleeds in Europe generally are 2 to 5mm from where the cut is to be made. This can vary from one print company to another. Some printers ask for specific sizes; most of these companies place the specific demands on their website or offer templates that are already set to their required bleed settings.
Source: Wikipedia
What should I consider when using copyrighted images?
You can read important information when using copyrighted images in this link http://www.ub.uu.se/use-the-library/digitization/copyright/