Query regarding order Types.

Hi ,
I'm running a script to place limit order with relative stopLoss and takeProfit.
I don't know why the order Type has been changing when ordered (Some times to Market order and Sometime to Stop Limit Order ) which is not as expected (If market order is placed StopLoss won't be applied to that) .What we need to do to fix this? (Is this the issue with API or the behaviour of the orders?).
is the orderId remains same at all points? 
why sometimes i'm getting an Executionevent with orderId 0 and sometimes positionId 0 ?