Magento 1.9 – Change Order of Input Fields in Billing Information

Try this,

Note : Don't Edit Core File

It will remove mandatory fields of First Name & Last Name.

UPDATE eav_attribute SET is_required = 0 WHERE attribute_code = 'lastname'

/app/code/local/Mage/customer/Model/Address/Abstract.php:

 /* if (!Zend_Validate::is($this->getLastname(), 'NotEmpty')) {
         $this->addError(Mage::helper('customer')->__('Please enter the last name.'));
     }
*/

/app/code/local/Mage/customer/Model/Customer.php

/*        if (!Zend_Validate::is( trim($this->getLastname()) , 'NotEmpty')) {
        $errors[] = Mage::helper('customer')->__('The last name cannot be empty.');
    }
*/

/app/code/local/Mage/customer/etc/config.xml

<lastname>
                    <billing>1</billing>
                    <shipping>1</shipping>
                    **<required>0</required>** // change from 1 to 0
                    <mapped>1</mapped>
     </lastname>

You can use various local storage mechanisms to store this data in the browser such as Web Storage.

The simplest and most widely supported is WebStorage where you have persistent storage (localStorage) or session based (sessionStorage) which is in memory until you close the browser. Both share the same API.

You can for example (simplified) do something like this when the page is about to reload:

window.onbeforeunload = function() {
    localStorage.setItem(name, $('#inputName').val());
    localStorage.setItem(email, $('#inputEmail').val());
    localStorage.setItem(phone, $('#inputPhone').val());
    localStorage.setItem(subject, $('#inputSubject').val());
    localStorage.setItem(detail, $('#inputDetail').val());
    // ...
}

Web Storage works synchronously so this can work here. Optionally you can store the data for each blur event on the elements where the data is entered.

At page load you can check:

window.onload = function() {

    var name = localStorage.getItem(name);
    if (name !== null) $('#inputName').val(name);

    // ...
}

getItem returns null if the data does not exist.

Use sessionStorage instead of localStorage if you want to store only temporary.

For More See here.