Obviously, I cannot comment on your questions about med - but I do have some insight to give.
From what I can read, it seems like a career in science research would be perfect for you. First, you seem really intent on doing maths - not only is doing maths highly encouraged in ANY science degree (maths is, after all, the language of science), any science degree worth its salt will actually have some level of maths made compulsory. (For example, Monash require ALL science students to complete one level one maths unit. Melbourne only accept students who have at least done methods into their science degree). Also, if you're that interested in maths, a science degree is the place for you to study/major in mathematics. That's one box ticked in your intent to study maths.
Secondly, you like the idea of learning about science, but not necessarily using it. I mean, you're interested in learning more, but upon the thought that medicine is less learning and more using, you've become wary. In scientific research, you use the science that you've learned about in university (that's the whole point of university, after all - learn applicable skills), but so you can learn MORE about science. This is your wanting to do less "applied science" ticked.
Finally, you seem somewhat interested in medicine, even if it's mainly research. Have you considered double degrees? If you take Monash's biomed/science degree, you can still learn about all the science you'll need for medicine (and then take the GAMSAT if you decide you want to be a medical doctor), but you'll have a whole science degree to fill with as much maths, chemistry, biology, etc. as you would like. However, here's another thing to think about - did you want to do med because of the biology/chemistry applications of science, or just because it was the obvious job for wanting to do science? Have you considered research in other areas, such as geology or physics? If your answer to this is "maybe research in other areas could be cool", I would suggest just taking a bachelor of science - planned properly, you can still go on to medicine/all the things you'd learn about in medicine, but you'll also get a chance to try these other areas of science which you might be interested in.