Please please tell me now

With Piglet being a weirdo and needing a special diet, the official version of which requires the relinquishment of several minor appendages for each purchase, I've been scouring the intermaweb for equivalent homemade foods. In the main it's been fairly successful and he seems to be doing all right*. But I have encountered one particular problem; the recipes are Merkin, and need translation into English measurements for convenience, so I started googling. This got me even more muddled, because it appears that, not only are our cups a different size to Merkin ones (ours hold 10 fl oz, theirs hold 8 fl oz), the weight of a cup varies according to its contents**. An American cup of plain flour weighs 4.3 ounces while a cup of rice weighs 6.5 ounces. A cup of salt weighs a whopping 10 ounces!

So this is where I'm calling upon my US friends for help. Please can you tell me the official weight of a cup of rice flour, a cup of soya flour and a cup of cornmeal. Also, is cornmeal the same as cornflour or not? And what on earth is 'unsulfured molasses'? Is there a similar product available on this side of the herring pond?

* crosses fingers, touches wood and spits over left shoulder
** stop sniggering, Mally