John: We publish the rates for payment in Bitcoin on a page of our website. This table automatically updates as the value of Bitcoin changes.
Gordo: I agree Bitcoin is presently not very stable. For these reason I don't hold onto very much of it. My strategy is to basically spend it when I receive it. Some merchants use services like Bitpay which results in a cash deposit to your bank account for every Bitcoin transaction received. Of course there is a cost (about 1%) for this service, so I prefer the direct method.
I had never heard of the hawala system. Bitcoin is peer to peer, therefore a lot like cash (except it can be sent online) where as hawala seems to involve brokers.
The number of merchants and vendors accepting Bitcoin is growing. Bitpay says they have over 10,000 merchants using their system. Here's a video showing the experience of buying cupcakes with Bitcoin.
I got to get back to work so I can't participate in this thread too much more. Definitely, Bitcoin is not for everyone, but so far it's been interesting for me.