Magento – Dislpay custom attribute in Product view page – in Product description template

1) All of the products in category 5 are showing instead of just 4.

{{block type="catalog/product_list" category_id="5" product_limit="4" template="catalog/product/random.phtml"}}

This is wrong. You're using the wrong block, catalog/product_list, you should be using catalog/product_list_random and the wrong arg product_limit, you should be using num_products. It's not exactly obvious, I don't know if I used google or checked Block/Product/List/Random.php and worked out what

$numProducts = $this->getNumProducts() ? $this->getNumProducts() : 0;
$collection->setPage(1, $numProducts);

was doing.

2) Though HTML and CSS appear to be identical on both pages, formatting is messed up as compared to the products in grid format as they look on a category page.

On the default product list page, the div hierarchy is

<div class="col-main">
    <div class="category-products">

On the homepage, when you include that block, the div hierarchy is

<div class="col-main">
    <div class="std">
        <div class="category-products">

.std has some rules that .category-products isn't expecting to override. For instance, if you changed from using the grid to the list layout, you'd be using an ordered list, and all the products would start displaying their list item number because this css

std.ol { list-style: decimal outside; margin-bottom: 1.5em; }

if overriding the default css of list-style:none which product-list is relying on.

Product collections by default load a subset of the products' attributes, unlike $product->load() which loads all product attributes. You have to make sure that the msrp attribute is loaded by the product collection you're using. See Mage/Catalog/etc/config.xml, the config/frontend/product/collection/attributes node:

In your module's config.xml you can add msrp:

<config>
...
    <frontend>   
        <product>
            <collection>
                <attributes>
                    <msrp />
                </attributes>
            </collection>
        </product>
    </frontend>
...
<config>

Alternatively, you can tap into the block that loads the product collection and do a $productCollection->addAttributeToSelect('msrp');. Another option is to also add an observer to the product collection load before event and again add the attribute to the select.

/Edit: If System -> Configuration -> Catalog -> Frontend -> Use Flat Catalog Product is enabled, product collections on the frontend read from the flat tables. That means that the attribute has to be one of the attributes indexed this way otherwise it will be silently ignored (addAttributeToSelect does nothing). An attribute to be indexed in the flat tables has to meet a few conditions that I don't remember exactly right now. I think the attribute has to be Used in product listing, Use in Layered Navigation and something else.

Cheers

/Edit: adding information from the comments

getAttributeText() should be used only for Dropdown and Multiple Select attributes. I'm pretty sure MSRP is a price type attribute. getAttributeText() eventually calls getOptionText() which returns false for regular attributes.

See Mage_Catalog_Model_Product::getAttributeText() and Mage_Eav_Model_Entity_Attribute_Source_Abstract::getOptionText()