If it were me, I'd possibly consider rethinking that bit about the title tag not mattering to Google.
Most search engine experts agree appropriate keyword use in the title tag is a very important factor for rankings in Google (and all the other major SEs as well). In fact, according to SEOMoz's search engine ranking factor survey
, "keywords in the page's title tag" was ranked by 37 top SEOs as the #1 most important Google rankings factor
It's also important because the contents of the <title> tag will generally be displayed in the SERPs. If the title reads well to humans and gets across the contents of the page well, it can help encourage a greater clickthrough rate from the SERP.
If your post titles already naturally contain keywords appropriately and display well in the SERPs (so as to encourage visitor clickthrough) then you may not need to set up a different <title> tag from the WP default.
But that's a far cry from saying the <title> tag isn't important.
You are right on one thing, though: the keyword META doesn't matter. You can leave that in or not, as you see fit. Google doesn't even index it, so it cannot possibly have any effect there.
Description META probably doesn't help with rankings, but with appropriate placement of the target key phrases in the description text, it appears as the snippet in the SERPs. With a bit of skillful copywriting, this can give you a chance to get a good marketing call to action appearing in the search results. While the description META itself might not have significant effect on rankings, that effective copy in the snippet can
have an effect on clickthroughs from the SERPs.