The builder for the most part works by changing g forces on a graph but you can use a piece-by-piece system for simple curved and straight track sections. Currently there is no way to get it on IOS but the developer has said that they will do it once they're able to get their hands on an apple device. And in terms of requiring a powerful device, you can change the resolution/level of detail of the track or download the 32 bit version (if you have an older phone) - not sure how it performs on other devices though since mine is pretty powerful, in videos I've seen it looks to run very well but yeah larger coasters may struggle
