You have some good answers already in terms of amazon affiliates

I actually use Fiverr more than anything else these days. If you go to flickr.com/search/advanced/ you can put in your search and then go to the bottom and tick the boxes so that you are allowed to use them commercially - you will have to attribute as per the creative commons license but this way you can search for the one's you can use.

Not sure about the music niche but I find plenty for snowboarding. Google images advanced search (as mentioned) is also good - and wikipedia commons is my other go to.

Not sure if you'll find any for your niche here but a member, Loes, put together a huge list. http://freeimages.siterubix.com/online-photo-sharing-sites-free-images-websites

Looks like you already found your answer. I am always looking for images for other things as well and it is not easy. The free Google images are not the best either. Try pixabay.com they have some free ones there also.

You will have to sign up with amazon as an associate and then you can use their images but you will have to promote their products in some way. As Michelle says google images are very good also.

If you are an Amazon Associate, you are free to use their images to promote Amazon products. Most affiliates work this way.

Have you tried using free Google Images? How to Use Google Images for your Website Safely

Yes, Google does not recognize punctuation, except in listing your keywords. If you have more than 1 keyword you would put a comma in between each so that it is recognized that there are more than 1 different keywords. So, "How to lose, belly fat "are 2 keywords, minus the ! which you do not use in your keyword list/

Hi. Google ignores punctuation, so comma's and so forth won't matter either way. It wouldn't be grammatically correct to put a comma in the example of "How to lose, belly fat today" though. :)