Not too sure about the 4 tube track question, but you can just look at picture or other Inverted impulse coasters to decide.
One thing that really sticks out to me is that the shaping of your dive loop is terrible. It isn't a smooth transition. It shouldn't rotate and then dive. It should rotate and start to dive at the same time so that by the time you at the height of the element it isn't fully rotated yet.
I hope that makes sense. If not, you can look at A113's surge and just go through the first element backwards but skip the downward roll part.
^ i got the impression that was intensional. And i personally would make it four tube track, depends on the speed and G's though, it's hard to say without riding it.