Avoiding dangerous duplication on a site about a very specific topic?

[etui342]

Sorry if this is covered often, but I didn't see it in a search here.

Let's say you have a site for a specific, technical product, like "silicone aircraft caulk." The site is a good 15 pages, thanks to individual pages on things like features, benefits, history, testimonials, scientific proof, etc.

With a product this narrow, it's almost impossible to avoid using the same keywords on every page -- because there are so few viable synonyms for this kind of thing. Is it okay if every page has "silicone aircraft caulk" as one of its keywords? Or does the penalty come in when you start to use LOTS of the same keywords over and over?

I suppose I can use some near-synonyms like "silicone aircraft caulks" and "silicone airplane caulk," but that only goes so far.

This is just for page rank on general search, not PPC. So I assume near-synonyms will work pretty well, right?

Finally, a basic question: should I put the product name as a meta keyword and use it in the meta description on every page? I assume Google somehow recognizes that it's a brand name and doesn't penalize for such a logical use of the word? I can't imagine not including it in the meta description at least, but this of course brings up the question of penalty for duplication.

I suspect my definition of "duplication" is a bit flawed overall?

Thanks!