Enhanced E-commerce helps improving tracking of an e-commerce website. It gives Statistics in variable measurements. It is not be used alongside analytics plugin, as this EE  Plugin also tracks pages.

Enabling Enhanced Ecommerce:

Admin Section of Google Analytics Property will have three sub-sections: Account, Property View.

To enable Enhanced E-commerce you need to navigate to View > Ecommerce Settings > Turn Status & Enable Related Products to "ON" and click Submit.

Sending E-commerce Data:

Your normal Analytics Snippet will look like

<script>
  (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
  (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
  m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
  })(window,document,'script','//www.google-analytics.com/analytics.js','ga');
  ga('create', 'UA-xxxxxxxx-1', 'auto');
  ga('send', 'pageview');
</script>

Here  ga('create', 'UA-xxxxxxxx-1', 'auto') will create a page object and  ga('send', 'pageview') will send the object to google tracker. So all the Ecommerce tracking will happen in between these Lines.

Add 

ga('require', 'ec');

to load e-commerce plugin, this should be after the creation of page object.

Sample Product List View Code :

ga('create', 'UA-xxxxxxxx-1', 'auto')
ga('require', 'ec');
ga('ec:addProduct', {               // Provide product details in a productFieldObject.
  'id': 'E60152',                   // Product ID (string).
  'name': 'Sandisk Pen Drive', // Product name (string).
  'category': 'electronics',            // Product category (string).
  'brand': 'Sandisk',                // Product brand (string).
  'variant': 'On-The-Go Pendrive',               // Product variant (string).
  'custom-dimension': 'custom-answer'
});
ga('ec:setAction', 'click', {       // click action.
  'list': 'Search Results'          // Product list (string).
});
ga('send', 'pageview')

Data Types:

1. Impression data - Data of product that is already viewed
2. product data -  Data of a product under view.
3. promotion data -Data of Promotion object
4. action data. - Type of Action

In our case scenario to Track Products Sales and views, we will use product data + Action data

Similarly,

Product Detail View :

ga('ec:addProduct', {               // Provide product details in a productFieldObject.
  'id': 'E60152',                   // Product ID (string).
  'name': 'Sandisk Pen Drive', // Product name (string).
  'category': 'electronics',            // Product category (string).
  'brand': 'Sandisk',                // Product brand (string).
  'variant': 'On-The-Go Pendrive',               // Product variant (string).
  'custom-dimension': 'custom-answer'
});

ga('ec:setAction', 'detail');         ----------> Action Data

Product checkout :

ga('ec:addProduct', {               // Provide product details in a productFieldObject.
  'id': 'E60152',                   // Product ID (string).
  'name': 'Sandisk Pen Drive', // Product name (string).
  'category': 'electronics',            // Product category (string).
  'brand': 'Sandisk',                // Product brand (string).
  'variant': 'On-The-Go Pendrive',               // Product variant (string).
  'custom-dimension': 'custom-answer'
});

ga('ec:addProduct', {
  'id': 'H25482',
  'name': 'Skull Candy Go Pro Headset',
  'category': 'Accessories',
  'brand': 'Skull candy', 
  'variant': 'blue',               
});

ga('set', '&cu', 'EUR');

ga('ec:setAction', 'purchase', {
  'id': '1054412477',                         
  'revenue': '37.39',                     
});

You can view this data in Reporting > Conversions > Ecommerce.

In case if you're facing any issues, you can use GA Debug, an official chrome plugin offered by Google to view data being sent. 

Tracking Site Searches:

This can only be possible if search queries are GET queries, where we use special terms like "q=<search-term>" or "/q/<search-term>/" .. etc.,

Navigate to View Section of your account and click on "View Settings", Under "Site Search Settings" , change "Site search Tracking" to on and query parameter as the keyword after which search keyword follows, like in both the above cases query parameters is: "q".

Now you can see all the queries being made in Google Analytics under Reporting > Behaviour > Site Search.