Boost converters are pretty simple - they exploit the back-emf effect of an inductor to get an output voltage that is higher than the input. Start with the basic circuit (inductor, switch, diode) and understand how that might work before worrying about what the control chip does.
https://en.wikipedia.org/wiki/Boost_converter
The reason the output voltage isn't explained on the IC's datasheet is simple: it's up to the designer. Think of that IC as being a bit like the 723, which is a linear regulator "kit" that can be used in a wide number of ways, depending on how you hook it all up.
The switch (as seen on the basic block diagram) is a transistor inside that IC. That has a maximum voltage rating of around 40V, so that puts a limit on how much output voltage you can achieve with just the IC. But if you add an external switch, then that sets the limit. You mention the IRF740 - that's what it's doing.
In short, that MOSFET is being turned on and off at many 10s of kHz by the IC. The duty cycle (the on time compared to the off time) is varied to regulate the voltage. It's magic, but understand how it works, and you'll understand the basics of all modern switched-mode power supplies
