I'm wondering what's the best practice if this involves storing html forms in Wordpress. I'm able to either keep code for that form inside a template file or I possibly could store it within the page content.

I don't be aware of technical ability from the finish admin user, in order to store it inside a template where he cannot edit and break it. Or I'm able to store it within the page content where he is able to edit and destroy the shape.

*Note this type is heavy styled as well as supporting javascript.

Not necessarily responding to the question - however when using forms in wordpress I'd you should consider using contact forms 7 wordpress plugin - its completely customisable and may have multiple forms anywhere in your wordpress site

@take advantage of is appropriate but he isn't responding to you question.

If you have to do this type custom unconditionally you have to think about the following:

Is someone of less technical savviness likely to have the ability to access your forms?

You might encounter plenty of problems if a person uses the visual editor to edit the forms. I would suggest storing it within the template if that's an problem.

Make use of a shortcode: Should you must store it inside a form you might want to convert it right into a shortcode and add it to your functions.php apply for your theme. This is best practice. Evaluate the shortcode API if you are unfamiliar with this: http://codex.wordpress.org/Shortcode_API

Most likely the easiest way to be able to allow your after sales user is produce a new shortcode. Allows refer to it as [showform]

Just see your functions.php and do:

add_shortcode( 'showform', 'showform_shortcode' );
function showform_shortcode($atts){
extract(shortcode_atts(array(
        'title' => '',
        'align' => false
    ), $atts));
$form='Your html form with title'.$title;
return $form
}

You may also use contact page 7 wordpress plugin for normal forms or paste the code in HTML mode

I additionally used execPHP wordpress plugin to incorporate files around the content. You are able to keep form.php inside your theme forlder after which within the HTML editor use:

<? include_once(STYLESHEETPATH.'form.php');?>

Hope it will help