Q: - How do I insert an image under the title of a widget?
A: Insert (by drag) a text widget into the widget area as shown on attachment. The text widget are at the bottom of Available Widgets shown on Appearance -> Widgets
Q: - Is there a way that I can have no title, but just have an image for the widgets on the home page?
A: Yes, please leave title blank (don't input anything).
Q: - How can I get rid of the footer widgets completely?
A: in front-page.php and page.php, remark the code like this:
<?php // get_footer(); ?>
Q: - How do I get rid of the small red bar right at the top of the page (all pages)
A: at line 29 in style.css, change to
Q: - How to I delete 'Leave a reply' on a page? I don't need this function.
A: in page.php, remark the code like this: <?php //comments_template( '', true ); ?>
Q: - I've made a page with a photo gallery on it. Is there a way that I can make the thumbnails bigger?
A: normally, gallery plugins are used instead of the default wordpress gallery. For example, I use NextGen Gallery plugin, which has options to change the size of thumbnails. if you are using plugins, it shall have the similar options, please refer to plugins author. If you would like to know more about plugins, wordpress has a quick document.