today it's may 21st and my homepage's cache was just updated in google, but it's written the cache image was taken on may 18th, though actually until just before it was saying it was last cached on may 13th.

why even if it was cached on 18th it was actually refreshed in google just today?

and another thing. on may 15th i've changed my website's keywords. the page was crawled by googlebot after that, but when i try searching for those keywords, my website doesnt appear within the results.

i've chosen very high KEI keywords, and for some of them my website should be the only result to appear in a search, but when i search for it my website still doesnt appear.

i dont think there are mistakes in the keywords, i've written them like
<META name="keywords" content="blablabla">
and i dont think i'm mistaking something.

any advice?