First image in post not shown (thumbnail)

Hello,

I have two questions regarding templates:
1) I tried to create a simple template, which shows only posts from a specific category. So I added the following to my template:
$query_posts(‘cat=8’);
get_template_part( ‘loop’, ‘index’ );

That works well so far, only that now the navigation isn’t working anymore, as I altered the main query with query_posts. So I tried to add the pagination with:
global $query_string;
$query_posts($query_string . ‘&cat=8’ . ‘&paged=’.get_query_var(‘paged’));
get_template_part( ‘loop’, ‘index’ );

After this, no posts are getting displayed anymore. Any ideas?

2) On all my posts, I inserted an image as a thumbnail. On the main page (front page), my posts are getting displayed as follows: Title, inserted image with alignment and text. The posts format by the way is set to “standard”. But on my new newly created page with the assigned template, only the title and the text are displayed, but no image. Of course I found a solution to programmatically add the image by myself, but why is it not there by default and how does the front page accomplish this?

Any help is much appreciated. thx!