both of these can be accomplished by editing the the cart display code by hand
In design View, right click on the weight column header, and select Table -> Delete Column
for the thumbnail, select the thumbnail text and co to code view. the code will look similar to:
<?php echo $eCart5->DisplayInfo("Thumbnail"); ?>
add an image tag around that
<img src="<?php echo $eCart5->DisplayInfo("Thumbnail"); ?>" />
you may want to add a hight or width as well.