Your failing require() problem seems unrelated to the BUWP plugin problems.
Line 17 in index.php (we're in WP 3.2.1, yes?) does indeed read
How did you get that "wordpress" prefixed to it?! I've no idea.
Maybe dig through http://www.php.net/manual/en/function.require.php . Glancing at it, I can't imagine how you got that weird error message, as if PHP failed to understand the relative path "./"? (But then, I _hate_ PHP, so pro'ly missing something.)
Anyway, this forum sucks (search results mostly obsolete, unresolved, uncategorized...), so generally I'd prefer asking in https://wordpress.stackexchange.com/ .
Hmm, note the timestamp on your errors, Nov-01. Could be they're stale, from an older WP version, or when you were messing with .htaccess, or something?