Subdomains and Google

[cothse]

<title>b a</title>
<title>a b</title>

With titles, the second title would rank the page better for "a."

www.a.com
a.b.com

With urls, would the second url rank the page/site better for "a" since "a" appears earlier as well?

[mails]

I'd recommend focusing more on basic SEO and quality content.