Try using the ruler tool. Set your carrier down and then set your waypoint and from there use the ruler to get that 90 heading. Might be other ways less cavemanish but it works for me.
I see you are asking IRL? as in once the yellow shirt in control give the point down the deck and the plane sits there in burn, why is it not propelled until the cat launches?
I think the lights you're referring to then are the position lights? The dial next to beacon and formation lights.
and I thought the same thing about Betty saying "engine right fire", but it happens.
It's really up to you.
Currently I use the yellow spring and then in game ad a curve of 20 with a bit of a dead zone as my yaw has a bit of play.
I've read some people do a curve of 25 but again you gotta kinda play with it to find a sweet spot for you.