Thanks for the mention, mouser
Kalos, I presume, these are 3 independent tasks. If your final goal is to something more complex that involves the 3 mentioned steps, people may be able to give you a more suitable advice. So:
1) People usually use a Clone or a Healing Brush tools for these tasks. The first one copies pixels from one place to another place (blending the edges) and it is suitable for removal of larger objects from photos. The second one is a specialized version of Clone that takes the surrounding of the replaced are into account - it work pretty well if the replaced area is small and the surroundings are simple. Photoshop even has a spot healing brush that does not require you to specify the source of the copied pixels. You'll find at least one the first tool in many free editors (including mine). Gimp also has a healing brush (I am unsure how good it is), so if you want all a free tool with all the options, grab Gimp for this task.
2) In raster editor? I have a lasso and polygon drawing tools in my editor that should work very well. In Gimp, you'll probably have to first select an area with lasso selection and then fill it with the bucket tool.
3) There are again multiple choices. Maybe a simple Posterize filter (found again for example in Gimp) will be enough for you (though I do not usually like these posterized photographs). If you are looking for something better (for example http://www.youtube.c.../watch?v=6KcCYHqLAB8
), you may need a vector editor like Inkscape. (I am working on allowing this kind of things in my editors, but it is not ready yet.)