You need to know the rated value of the inductor, that will tell you how much current you can take. yes it takes all the current. It needs to be rated so your maximum current is not more than 70% of the rating.
Switch mode power supplies are very sensitive to circuit layout, without a good PCB it is almost impossible to get a reproducible circuit. Even with a good PCB layout I have seen many professional engineers take two or three goes at getting it stable under all current draws.
That is why you are better off buying a ready built module for this sort of thing.