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Both Shane and Nakul gave some good advice, so I'll just add my 2 cents. As your domain is new, this could have serious implications for your site and it's ability to rank. I can't say for certain it would hurt, but it sure would make it a likely candidate for an algorithmic penalty. 302s sound better than 301s to me, but even that many 302's redirecting to such a young site should throw up spam warnings galore at the Googleplex. Additionally, adding the extra layer of his site... typindomain.com ---> hisredirectsite.com ---->mysite.com ...might actually complicate things instead of making them better. In the end, I think there might be easier ways to gain the same amount of traffic in a long-lasting, low risk way.

Yes, I understand. I would check the domains being redirected to see if they have any history associated with them. If they have been linked from anywhere on the web, then Google knows they exist. If not, they are pretty much (almost) like brand new domains. This process would also make sure and help you find if there was nothing fishy/spammy going on with those domains in the past. I would still do a staggered redirect depending upon how many you are planning to do. As you said few dozen, I would just spend some time looking them up and based on the results, select the ones that have most type-in traffic first. And then in a few weeks, check to see how it's working for you and if you want to redirect more of those.

Its thin as a % of all the pages on your site. If your ratio of thin to thick content is wrong, you can get hit. So a thin homepage is no problem if the rest of your site has good content

I agree with Egol's comment. That's the way to go. Optimized Filename, Anchor Text and any surrounding text...think of trying to describe the image in 3-4 words. It works wonders. And if people share your image or the page the image sits on, it helps. Also, I have not seen a clear evidence of Images XML Sitemap helping or not helping, but it can't hurt to do an XML Sitemap of Images/URLs along with their captions/titles if you can. <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" <="" span="">xmlns:image="http://www.google.com/schemas/sitemap-image/1.1">        <loc>http://example.com/sample.html</loc>     image:image</image:image>         image:lochttp://example.com/image.jpg</image:loc></urlset> http://googlewebmastercentral.blogspot.com/2010/04/adding-images-to-your-sitemaps.html