Thanks for the clarification. Are Spot FX actually "one day" forward contracts that are based on buying the other currency on a 1:100 leverage and being exposed to any change in conversion rate? If so, I don't see it as a hedge but rather as a speculation... Also, the other side of the trade for both Spot FX and Forward FX seems to be a certain dealer so that there is a counterparty risk -- if the dealer goes bankrupt (which is not an unimaginable scenario) then you may not see your money. However, in futures FX which are traded through central exchange there is almost no counterparty risk, since the other side of every trade is the exchange's clearing firm. Is it correct?
If I transfer USD to EUR through IB account, do I actually make a FX spot transaction and therefore I am fully exposed to IB's credit risk (and I assume this is not insured under the FDIC deposit insurance)?
If you trade spot through Interactive Brokers, you settle overnight, so you will get Euros (and can withdraw them the next day if you want.) If you buy a forward contract, you can still get your money out early, but at whatever the rate is at the time ( IB's accounts are not FDIC insured though. However, they have a very strong financial condition - if IB goes out of business, you probably have a lot worse problems to deal with! Their customer service can probably answer your specific questions better than I can.