For the image part, at least, you should use api instead of managing pathes by yourself (which is non only ugly but dangerous : what if you change your imagecache preset? or your filesystem architecture?).
For instance, that's my version (I think the good way is to do it entirely with a theme function, but it's easier to begin this way) :
<!-- Start Product -->
<!-- Start Prices section -->
<?php
// maybe there's a better way to do this part, using theme functions
// but I've only found individual formatting, with "theme_uc_product_price" function
// here I use Ubercart Discounts (Alternative)
$sell_price=$node->sell_price;
$reduced_price=$node->field_product_reduced[0]["discounted_price"];
$codeless_discount=$node->field_product_codeless[0]["codeless_discounts"];
if ($reduced_price){
print '<div class="product-info product display">';
print '<span class="uc-price-product uc-price-display uc-price original-sell-price">'.t("Original price")." : ".uc_currency_format($sell_price).'</span>';
print '<span class="uc-price-product uc-price-display uc-price ">'.$codeless_discount." : ".$reduced_price.'</span>';
print '</div>';
}else{
print '<div class="product-info product display">';
print '<span class="uc-price-product uc-price-display uc-price">'.uc_currency_format($sell_price).'</span>';
print '</div>';
}
// Feel free to add other prices here
?>
<!-- End Prices section -->
<!-- Start Main informations -->
<?php
// product title
print "<h2>$title</h2>";
// product description
// if you want to customize how your fields are rendered, use $node->content['YOUR_FIELD_NAME'][0]['#view'];
print $node->content['body']['#value'];
?>
<!-- End Main informations -->
<!-- Start Images section -->
<?php
// if you need a more advanced customization, override the themeable "theme_uc_product_image" function (uc_product.module)
if ($node->content['image']['#access']==1) print $node->content['image']["#value"];
?>
<!-- End Images section -->
<!-- Start Weight section -->
<?php
// again, if you need a more advanced customization, override the themeable "theme_uc_product_dimensions" function (uc_product.module)
if ($node->content['weight']['#access']==1) print $node->content['weight']["#value"];
?>
<!-- End Weight section -->
<!-- Start Dimensions section -->
<?php
// again, if you need a more advanced customization, override the themeable "theme_uc_product_dimensions" function (uc_product.module)
if ($node->content['dimensions']['#access']==1) print $node->content['dimensions']["#value"];
?>
<!-- End Dimensions section -->
<!-- Start Button section -->
<?php
// there's a themable function theme_uc_product_add_to_cart, and I think you still can alter uc_product_add_to_cart_form function
print $node->content['add_to_cart']["#value"];
?>
<!-- End Button section -->
<!-- End Product -->