Is-it-possible-to-indicate-order-size-in-PlaceTrade

I am confused by this as follows:
A Transaction instance is returned by PlaceTrade.
One can then set in the next line transaction. Quantity = 10.
But is it not too late to fix qty after PlaceTrade?

This probably has to do with the comment in the PlaceTrade description;
"Places a simulated order, and returns an instance of the Transaction class the represents it. "

If PlaceTrade only places a simulated order then it is possible to define qty after the fact. Then my question is: how does one place a real trade? For example for Schwab? Are the names different for each broker? Or, is there a generic name for real trades?

Thanks!

Your Strategy uses PlaceTrade to place a simulated order in a backtest.

Such orders that are placed on the last bar of data, which are intended to be executed on the next future bar, become Signals that show up in the Signals pane.

You can then Place these Signals to a Broker by selecting them and clicking Place. Or you can configure a tool like a Streaming Strategy Window, Strategy Monitor, or Quotes, to automatically place Signals.

I get the part about (PlaceTrade then Transaction specification) => order for the next bar.
If I may ask a couple of follow up questions:
- I am using ^SPX bars to generate signals to trade SPY options.
Can I set transaction.SecurityName = option name for an option trade?
- Can I use this method in a (streaming chart + myStrategy)?
- Where can I find the Signals pane?
Thanks!