Spencer Finnell

In a lot of cases, categories without any posts in them are not shown by default. Are the categories that you can’t see populated with posts?

As long as you have a backup of your database, you shouldn’t lose anything. Your site should still function without the /wp-admin/ folder, you just won’t be able to log in. You should just be able to reupload the /wp-admin/ folder to via FTP.

I have no idea why they would randomly disappear. When you get back in, you should change/update your passwords for both your WordPress login, and your FTP/Databases.

There likely won’t be anything that is align:left because that is how text is aligned by default. You want to look in the HTML and find the div that wraps the post. Then find that in the CSS, and add text-align:center;

Removing it from single.php will only remove when you are viewing an individual post. You need to remove the unwanted stuff from loop.php as well.

You would have to check the Thematic page for a list of changes for the upgrade. Then you can decide yourself whether or not to update. But generally, it’s good to have the latest version.

Do you have some sort of comment security plugin installed? There is no security code on the default comments.

On archive.php you could use query_posts to change how many posts are displayed. Read more about query_posts.

Does it happen every time you view those pages? Or only sometimes?

Yes.

ThemeShaper (the Thematic People) explain how to use a child theme which allows you to create a separate theme from Thematic, but still use Thematic as a framework.

In the future you should make all modifications to a child theme, so when an update to the framework comes out, you can easily upgrade the framework, but keep your modifications.

Here is an article that goes over how you can exclude a certain category from different parts of your site.

You could also try this plugin, or this one.

It jumps to the next line for me too. The only way you can be sure it will stay on one line is to reduce the margin in between each item. Right now you have 16px in between each line, but even reducing it to 15px made them all stay on one line.

You should add margin:0; padding:0; to #navigation ul which could free up some space.

If you are comfortable post a live example, it would be easier.

Twenty Ten uses the_content if you are not on a search or archive page, but otherwise shows the the_excerpt

<?php if ( is_archive() || is_search() ) : // Only display excerpts for archives and search. ?>
	<?php the_excerpt(); ?>
<?php else : ?>
	<?php the_content( __( 'Continue reading <span class="meta-
<?php endif; ?>

So you can just take out that the if statement if you always want to show everything.

<div class="entry-content">
	<?php the_content( __( 'Continue reading <span class="meta-nav">&rarr;</span>', 'twentyten' ) ); ?>
	<?php wp_link_pages( array( 'before' => '<div class="page-link">' . __( 'Pages:', 'twentyten' ), 'after' => '</div>' ) ); ?>
</div><!-- .entry-content -->

Some browsers render things slightly differently (text size, etc) so if your total width of navigation items is very close to the total width of the navigation, certain browser quirks might cause the navigation to expand a few extra pixels, making the last item not fit correctly.

Try deactivating all plugins without adminstrative access.