Enqueue Wordpress Core jQuery at Footer

Hi,

Im trying to follow Google PageSpeed Insights suggestions and increase the PS Score.
This is about render-blocking JavaScript in above-the-fold content
Thing is I don't really know php or coding. I have a general idea and I read lot of tutorials and played with the code and I managed to fix above Google PS error.

Problem is Im not sure how it will affect my site/ consequences.

I edited the functions.php file of my theme. I pasted image + code Before and After I made the changes at end of the post if you want to take a look. Also list of plugins.

These are my questions.

01. As I copy pasted codes, I would like to know how those changes will affect my site? What could possibly go wrong? Where are the places I should check to see if something went wrong? Will there be any conflicts?

02. Before I made changes, there were two files in the header (i.e. jquery.js AND jquery-migrate.min.js).
After making changes I only see jquery.js in the footer.
Should I worry about this?

03. Lets assume something went wrong. Judging by the codes I modified, are they irreversible or undoing the changes will fix it?

I wanted to ask these before I make these changes in the real site.

Thanks.

____________________________

BEFORE

Google PSI: http://i61.tinypic.com/s77p.jpg

CODE:

function maya_classifieds_front_scripts() {
wp_enqueue_script('jquery');

wp_enqueue_script('maya-nuslider-js',JS.'/jquery.nouislider.min.js', array('jquery'),'1.0',true);
wp_enqueue_script('maya-ad-genral-js',JS.'/maya-classified-genaral-script.js', array('jquery'),'1.0',true);
wp_enqueue_script('maya-view-switcher-js',JS.'/maya-adspot-popup.js', array('jquery'),'1.0',true); //custom list/grid view switcher script and popup window script
 wp_localize_script( 'maya-view-switcher-js', 'classfiedAjaxParam', array('themeurl'=>THEMEROOT,));
 wp_enqueue_script( 'jquery-form',array('jquery'),false,true );
 wp_localize_script( 'jquery-form', 'jformparam', array( 'ajaxurl'=>admin_url( 'admin-ajax.php' ),));
wp_enqueue_script('maya-genaral-js',JS.'/theme1-genaral.js', array('jquery'),'1.0',false);

PHP:

____________________________

AFTER

Google PSI: http://i57.tinypic.com/t0oxh2.jpg

CODE:

function maya_classifieds_front_scripts() {
  wp_deregister_script( 'jquery' );
  wp_register_script( 'jquery', includes_url( '/js/jquery/jquery.js' ), false, NULL, true );
  wp_enqueue_script( 'jquery' );
wp_enqueue_script('maya-nuslider-js',JS.'/jquery.nouislider.min.js', array('jquery'),'1.0',true);
wp_enqueue_script('maya-ad-genral-js',JS.'/maya-classified-genaral-script.js', array('jquery'),'1.0',true);
wp_enqueue_script('maya-view-switcher-js',JS.'/maya-view-switcher-popup.js', array('jquery'),'1.0',true); //custom list/grid view switcher script and popup window script
wp_localize_script( 'maya-view-switcher-js', 'classfiedAjaxParam', array('themeurl'=>THEMEROOT,));
wp_enqueue_script( 'jquery-form',array('jquery'),false,true );
wp_localize_script( 'jquery-form', 'jformparam', array( 'ajaxurl'=>admin_url( 'admin-ajax.php' ),));
wp_enqueue_script('maya-genaral-js',JS.'/theme1-genaral.js', array('jquery'),'1.0',false);

PHP:

____________________________

Plugin list
https://wordpress.org/plugins/admin-menu-editor/
https://wordpress.org/plugins/alchemist-ajax-upload/
https://wordpress.org/plugins/contact-form-7/
https://wordpress.org/plugins/dx-delete-attached-media/
https://wordpress.org/plugins/frontend-edit-profile/
https://wordpress.org/plugins/google-sitemap-generator/
https://wordpress.org/plugins/image-cleanup/
https://wordpress.org/plugins/meta-box/
https://wordpress.org/plugins/options-framework/
https://wordpress.org/plugins/regenerate-thumbnails/
https://wordpress.org/plugins/simple-image-watermark/
https://wordpress.org/plugins/simple-share-buttons-adder/
https://wordpress.org/plugins/tinymce-advanced/
https://wordpress.org/plugins/user-role-editor/
https://wordpress.org/plugins/wc-shortcodes/
https://wordpress.org/plugins/wordpress-importer/
https://wordpress.org/plugins/wp-pagenavi/