It is 'top of book' but you don't jump in line. Example: Market is 0.25 - 0.50 You send a LMT order to sell @ 0.50 Trades are printed at 0.50, but your order remains unfilled. As soon as the market turns to 0.50 - 0.75, your sell limit order is filled (at 0.50).
%% YOU have probably noticed also; your guts + anyone with sense, knows the difference in gut feel on real money/real profit /\real loss + a simulator. But that one gentleman that get's consistant bad fills on his simulator/that could actually help[price improve many times that way/LOL]
While showing a friend price action of Crude oil in a simulated account we laughed and joked while sipping cappuccino. 10 minutes later in my live account I was cursing at the computer screen. Yup. no difference at all.
End of the queue? Do you mean demo orders are actually part of the direct access system? Or are the orders sent to live and demo servers separately?
Number of people have posted above that demo is unrealistic as it ignores slippage etc.. This is true enough but only really significant if you're trading very short time-frames. So the failings of demo are a moot point for new traders - you shouldn't be trying to make money scalping at all.
Slippage is a pittance compared to psychological effects. Demo (as in demonstration) is great for learning the platform. Reality is great for learning to trade. There is no substitute or surrogate.