To place the add to cart form on your entity page place the following code into entity.gridwithprices.xml.config wherever you want it to display:
Code:
<xsl:value-of select="aspdnsf:AddtoCartForm(ProductID, VariantID, 0, 'right')" disable-output-escaping="yes" />
Note: I'm pretty sure this can cause issues if you're displaying a product with multiple variants and/or color-size options. I think it only adds a default variant to the cart, although I am not certain about the actual behavior.
You can change table/cell attributes inside the XML package. Look for the appropriate <table> <tr> and <td> elements and apply attributes as you see fit. You'll most likely be interested in the HTML contained within the <xsl:template name="ProductCell"> template area.
You're probably safe altering the stock XML package if you aren't making any drastic changes. Just make a backup copy of the XML package first so if you do end up hosing it you've got a restart point.
Running: AspDotNetStorefront ML 8.0.1.2/8.0.1.2