You are going about this pretty much all wrong. You should read the instructions before continuing.
An Introduction to Child Themes
An Introduction to Hooks in the Genesis Framework for WordPress
The second code you provided can be rewritten as this:
// Template Name: Page Template
genesis();
That’s it. Genesis takes care of all that stuff you just wrote. But you need to read the instruction. Watch the video in the second link. You are making this much harder than it has to be.
***Update … instead of having the Content of the page. I want the list of Post[s] with excerpts …. [sic] How can [I] do that?
I couldn’t stand the idea of naming a page template Page Template.
<?php
// Template Name: Excerpts
// Replace the loop.
remove_action( 'genesis_loop', 'genesis_do_loop' );
add_action( 'genesis_loop', 'genesis_custom_loop' );
// Change the content archive and loop args.
add_action( 'genesis_pre_get_option_content_archive', 'child_post_content_archive' );
add_filter( 'genesis_custom_loop_args', 'child_loop_args' );
genesis();
/**
* Change default content to excerpts on this page.
*/
function child_post_content_archive() {
return 'excerpts';
}
/**
* Use WP_Query args.
*
* @link {http://codex.wordpress.org/Function_Reference/WP_Query}
*/
function child_loop_args() {
return array(
posts_per_page => 5,
);
}