Errors in Twenty Eleven theme

Hello Otto,

I do not create themes, but have made several child themes for WordPress themes. I recently came across your Theme Check plug-in by accident and decided to run it. I have two sites running on Twenty Eleven child themes and found about a dozen errors on each. On scrutiny I noticed that the 10 of the errors appear to be thrown up by the Twenty Eleven theme itself. Here are the errors without the child theme

REQUIRED: The theme must not use the <title> tags.
REQUIRED: The theme must not call to wp_title().
REQUIRED: The <title> tags can only contain a call to wp_title(). Use the wp_title filter to modify the output
REQUIRED: No reference to add_theme_support( "title-tag" ) was found in the theme.
REQUIRED: Found a Customiser setting that did not have a sanitisation callback function. Every call to the add_setting() method needs to have a sanitisation callback function passed.
REQUIRED: screen_icon() found in the file theme-options.php. Deprecated since version 3.8.

Line 335: <?php screen_icon(); ?>

REQUIRED: get_current_theme() found in the file theme-options.php. Deprecated since version 3.4. Use wp_get_theme() instead.

Line 336: <?php $theme_name = function_exists( 'wp_get_theme' ) ? wp_get_theme() : get_current_theme(); ?>

REQUIRED: add_custom_image_header() found in the file functions.php. Deprecated since version 3.4. Use add_theme_support( 'custom-header', $args ) instead.

Line 159: add_custom_image_header( $custom_header_support['wp-head-callback'], $custo

REQUIRED: add_custom_background() found in the file functions.php. Deprecated since version 3.4. Use add_theme_support( 'custom-background', $args ) instead.

Line 160: add_custom_background();

REQUIRED: add_contextual_help() found in the file theme-options.php. Deprecated since version 3.3. Use get_current_screen()->add_help_tab() instead.

Line 137: add_contextual_help( $screen, $help . $sidebar );

I also checked and found that some of these errors still occur in Twenty Fourteen.

My child themes have been working well for more than three years. My question is, is it possible to correct any of these errors with code in my child theme or should I just ignore them?