You guessed right.
I would recommend reducing the car count to 5 since the only B&M Launched Wing has the 5 car due to weight
I'm using a little artistic license here. I'm not a big fan of the shorter 5 row trains aethetically. I love the gracefulness of a larger train, so opted for 7 as a happy medium. I had to weigh up reality with what I wanted. You're probably right about the power needed to launch such a large train but I'm sure it's do-able...somehow.
its hard to tell what the second element is from the first set of pictures - is it a sort of stengel dive?
I'm not sure it counts as a stengel dive as it incorporates more air-time. I've taken it from Parrot Coaster and Fury 325's turn around. I tend to treat creating my B&Ms as a recreation of elements sewn together into a layout of my own. I loose originally points usually, but it's what I enjoy in a good realism NL coaster. The phrase "what would B&M do?" is a running theme with my design usually =/ (and my life obvs).