supply/demand dynamics same as stocks?

[philipk]

I'm trying to better understand why prices of a given currency change. Does it work exactly the same as stocks?, is there a fixed amount of, let's say, Yen, similar to shares outstanding of a given stock.

And most of the time are dealers matching orders with other traders or are they buying for/selling from their own inventory. Who am I really betting against? The market or my dealer. (this conflict of interest is one of the things that bothers me).

Also how are they "compensated through the bid/ask spread" If I buy the $/Yen at 1.1111 (ask) how did the dealer already lock in profit if I still hold the position. Can someone help me understand exactly how they profit off of the spread?

apologies if these answers are on the site somewhere

thanks,
Philipk