You could use the Feed for that Blog’s category to import into a different Blog. This seems straight forward. You can also do this for tags.
Commenting plugins exist for whatever platform you want to use. I use Disqus (has FB, twitter, video, openid support) but Backtype is another good choice.
I have the same issue (unexpected T_STRING is in line 17 of my wp-config.php file) upgrading from 2.3.2 to 2.6. I have multiple blogs’ tables in 1 DB. I am only upgrading one of these as a test. wp_db_version seems to be updated in /wp-includes/version.php to 8201 which indicates a WP 2.6 schema level. but upgrade.php returns blank as does other scripts.
