I have one major piece of advice: trade with a NFA regulated broker.
Personally I have experience with Oanda and IBFX and I think that Oanda might be what you’re looking for. At least they fulfill your criteria. Be advised on their weak spot - the charting.
Many use Oanda for the trading and a MT4 demo for the charting.
Hey aquablue! you can try my broker - WSD. Although it has a delaing desk, but don’t really need to deal with them, after you have downloaded their platform. I suppose the ability to trade on chart with their platform and their competitive spreads might entice you towards them.