How to get images into search engines

[parade]

I would appreciate tips on how to alert search engines, esp. the google imagebot, to the existence of my images, as that is a primary way people shop for both plants and handmade soaps, my main sales items.
Google's found and indexed my site, it comes up in the first page or as the first hit on many searches, good; but my images--that's different.

I have signed up with the google webmaster service, and see no crawl or robot errors--added a robots.txt file set to allow all; and have waded through google's dense webmaster help pages which don't say much beyond urging me to sign up for the enhanced image search. I did that but there has to be more that I am missing.

Searching on this topic on several fora has led me to these conclusions, so if I'm wrong, please chime in and clear things up!
1) images must be linked to get noticed at all by any search engine
2) google wants those images to have alt text
3) captions near the images are good
4) image name means nothing. No wait, it means everything. ??
5) better be .jpg files
6) pages must have corresponding keyword text relating to the images you're trying to get seen (that seems obvious, but we're all doing our pages differently. . .)
7)the alt text attribute should have keywords but how many?
8) things seem to vary quite a bit with yahoo, ask, etc.---???

---so, even if you have gorgeous photos of lovely things, if they don't have a link to them, they might as well be in the 4th dimension?
What does this mean for photo gallery pages?
If I want to have a page of popular plant offerings, with the name of the plant, do I have to have links to those images from elsewhere? Would an index of photos list on the page work, or would that be perceived as spamming the robot?

Thanks in advance----

[Matt]

Are your images beginning to turn up in the search engines now after we removed the hotlink protection from your account? Enquiring minds want to know...

[parade]

No, not yet. They have made it into the google cache now though, and the pages have gotten more #1 listings, but even searching for a specific image title doesn't net me any--of the ones I have tried. But I expected it to take a while--I guess I don't know how often the image indexing process takes. Too, some of the image categories seem almost spammed by certain businesses, filling up several pages of the image search results with ultra similar if not the same, images. Hard to compete with that.