Hey,
1) Delete following code in template_blog.php:
<?php comments_popup_link('No Comments', '1 Comment', '% Comments'); ?>
2) No it's not easily possible because of the html and css structure of the Display theme.
3) Open up template_contact.php and add your input fields before following code:
<p>
<input type="hidden" id="myemail" name="myemail" value="<?php echo $email_adress_reciever; ?>" />
<input type="hidden" id="myblogname" name="myblogname" value="<?php echo $name_of_your_site; ?>" />
<input name="Send" type="submit" value="Send" class="button" id="send" size="16"/></p>
I'd suggest to use a contact form plugin like "Contact Form 7" or cformsII though because it's easier than adjusting the contact form template.
4) You can use the "Custom Post Template plugin" to select individual templates for your posts/portfolio entries. You can download it here:
http://wordpress.org/extend/plugins/custom-post-template/
Afterwards upload the plugin files to your wordpress „plugins“ directory (located under wp-content/plugins).
Now you need to create a template:
a) Just make a copy of single.php, rename it to fullwidth_post.php and paste the following code before the first code line.
<?php
/*
Template Name Posts: Fullwidth
*/
?>
b) search for following code in fullwidth_post.php:
$k_option['custom']['bodyclass'] = ""; // $k_option['custom']['bodyclass'] = "class='fullwidth'";
and replace it with:
$k_option['custom']['bodyclass'] = "class='fullwidth'"; //$k_option['custom']['bodyclass'] = "";
Afterwards delete following code:
<?php get_sidebar(); ?>
Now you can selectthe fullwidth template on your portfolio post editor page.
Create a new thread and tell me what problems you are encountering and what you want to know. 
There is no step 3 :) 
