I dont recall a version of eCart that did not have a Dreamweaver UI, Please send a copy of one of the add to cart pages and the cart display page so i can take a look at the code.
as far limitations to Cookies based carts, all browsers have a maximum size that a cookie can be.
for example in IE, the maximum size of a cookie is 4096 bytes:
306070
in eCart, there is the option to store the cart information in a session variable or use a cookie, we recommend using the session for storing the cart because it does not have the size limitation.