The hook will allows to limiting display long characters (as defined in condition) for Question view and will add `read more` link. It will expand all question content when click on read more link.

q2am-add-readmore-to-question-view.php

<?
/*
 * hook: 			Add read more link to the question view q-content
 *
 * hook by:		Q2A Market
 * author: 		Jatin Soni
 * url:				http://www.q2amarket.com
 * version:		1.00
 * 
 * Description:
 * The hook will add 'read more' link to the
 * question's content after defined number of characters
 * and hide rest of the characters.
 *
 * usage:
 * Place below code into your theme or plugin layer
 * 
 * function q_view_content(){}
 * 
 * Disclaimer:
 * This program is distributed in the hope that
 * it will be useful, but WITHOUT ANY WARRANTY;
 * without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.
 * 
 * See the GNU General Public License for more details.
 */

public function q_view_content($q_view)
{

	if (!empty($q_view['content'])) {

		$this->output('<div class="qa-q-view-content">');

		// remove div tag from content
		// but there is a risk if someone add
		// div within the content
		$tag = 'div';

		// Again adding entry-content to support core
		$this->output('<div class="entry-content">');

		// displaying content based on character count
		if (strlen(strip_tags(preg_replace("/<\/?" . $tag . "(.|\s)*?>/", '', $q_view['content']))) > 100) { // change 500 with your number
			
			$this->output('<div id="descitem">');
			$str = substr(preg_replace("/<\/?" . $tag . "(.|\s)*?>/", '', $q_view['content']), 0, 100) . '...<a href="#" id="readmore">read more</a>'; // change 500 with your number
			$this->output_raw($str);
			$this->output('</div>');

			$this->output('<div id="fullcont" style="display:none">');
			$this->output_raw(preg_replace("/<\/?" . $tag . "(.|\s)*?>/", '', $q_view['content']));
			$this->output('</div>');

		} else {

			// this will output content without readmore
			// if there is less then defined character count
			$this->output_raw(preg_replace("/<\/?" . $tag . "(.|\s)*?>/", '', $q_view['content']));

		}

		$this->output('</div>'); // end of entry-content
		$this->output('</div>'); // end of qa-q-view-content
		//javascript to show hide divs
		$this->output('
			<script>
				$("#readmore").click(function(){           
					$("#fullcont").show();
					$("#descitem").hide();
					return false;
				});
			</script>
		');
	}
}