Don't use free clipart for your brand mascot. Think about it - do you want everyone else in the world using the same cartoon character you are? If you go the clipart route to save money, instead of having a custom character designed for you, be sure to go to one of the clipart developers that specialize in brand mascots so the character you choose is not in the public domain where anyone can use it for free. A good site for royalty free brand mascots is Toons4biz.com.
Christmas stationary: one could paste Christmas images such as trees, Santa or snowmen onto the stationary and create a beautiful Christmas stationary
Some designers actually make their available online in its original format, so that you can download it and make some changes, as well as resize it, though most will only supply a high resolution version that can be used up to a certain size poster. A Google search for.svg clip art will give you vector art you can use in Inkscape, and in fact some of it is exceptional.