I have a mazda3 that was recently damaged by the bolt on a garage door.  It wasn't an impact but the bolt mark was imprinted on the plastic bumper.  The car slowly slided toward the door and I opened the garage door without knowing.  It left two deep gouges and an imprint of bolt.  I think it was so deep, it even removed the primer because I can see the black plastic (the white markings are from waxing over it). 

Question is, what level of difficulty on a scale of 10 is this to fix for someone who has no experience with bodywork.  I can detail and polish the car but I haven't done any filling, touching up before. 

Also, I only want to repaint that one section instead of the entire bumper.  Would it look every different then the rest?

You are going to have to fill the dents with filler, and smooth the area before painting. If you take your time and keep at it until it is really smooth, you should be able to have a nice job. Degree of difficultly? Probably 4 or so if you have no experience. (For an experienced body person, virtually no difficulty here at all.)

I'd paint the entire bumper if you want a really nice job though. Metallics need to be blended and there is just no good place on a bumper to blend into so paint the whole bumper.

I had to chance to work with a car today that needed to be sanded.  We wet sanded the entire car for two days by hand using a block.  So by now I am pretty confident about blocking sanding.  But i am still unsure about the painting process.  I know it takes skills to have something painted to match the rest of the car and this is what I am lacking.

Although I was able to find a place in town that will rent out paint booths for $10/hour.  So should I still tackle the job?

Sure, just follow the directions on our site. I would practice off the car first before you paint for the first time to get the feel of it.