Google does not own the images that are shown when u do a search. The images are form many sites and directories and so on, that are owned my the one that owns the site itself. So yes, it could be bad, because the img can be copywrited and cand get in trouble. Always use free directories of images that let u to use the img as u want and give u the wright to do it
Google never crawls the images. However you should use free images. You can't use some images which will copy right images.
no dont do that because certain pictures on the google are strictly copy protected and they ll get to know it. instead search for an alternative. all the best
Would you like it if someone Googled your articles and used them in their own projects without asking or paying you?
You can use them of-course. But they should not be copy-rated moreover avoid them if they do have watermark on them. You can do some changes on these photos with the help of photo editing software like Irfan view.
I will suggest you that you should download images from websites offers you free. A unique photo for your website always leave good impression on visitors. And try to avoid pictures from Google because some the pictures are copy right protected and finally your website holds in sandbox.