They are usually paid per view, but can they also be paid per click? Do text ads generally pay better or worse?
That's strange...it's a pay per click all these while. Although there are different arguments as to whether text or image ads pays better, I feel that this is somehow related to the niche you are in and it also depends on the bids made by the advertisers.
no one can really tell which is better, it depends on advertisers what bids per click they have kept while ordering campaigns
It would depend on the page views in my opinion, if the site has a lot of page views and the contextual ads arent getting any clicks at all maybe it would be worth trying with ads images as they usually tend to be on cpm mode.
Text generally pays better because they have to pay more vs. images. Images have less competition usually. Keep in mind though, images sometimes will give you better CTR too.
i believe it's niche specific on which is better. if you have lots of text content that requires reading, then you'll be better off with text. if you have lots of graphical elements then images are better. i often hear that gaming sites do better with image ads.