Using html inside of Pages

Hello

I am using a child theme of the new Twenty Thirteen Theme, very good I must add.

I have been creating custom page templates for individual pages, however I have found myself adding code to my pages from within the CMS under Page > Add New Page
for example
<code><div class=”container”><p>Some content!!</p></div></code>
This makes me feel uneasy!
Is this good practice to do this? Because sometimes when I re visit the page from within the CMS, extra characters have been added. For example additional <ul> tags.

Is it possible to call the content from within the custom page template and echo out the individual paragraphs into their respective “container” classes?

Template extract

<div class="entry-content">
		<div class="custom-slider">

		</div>
		<?php the_content(); ?>
		<?php wp_link_pages( array( 'before' => '<div class="page-links"><span class="page-links-title">' . __( 'Pages:', 'twentythirteen' ) . '</span>', 'after' => '</div>', 'link_before' => '<span>', 'link_after' => '</span>' ) ); ?>
		</div><!-- .entry-content -->
		<div class="container">
		//echo some content here
		</div>
		<div class="container-1">
		//echo some content here
		</div>
		<div class="container-2">
		//echo some content here
		</div>

The standard way <?php the_content(); ?> calls all the content as a block.
Or is there a better way? For example using widgets or would this affect SEO? – Hope someone can advise! Thanks