My travel into reflex photography continues, more and more interesting and fun

I have some basic questions, or some I belive are such for anybody with little experience, and yet I could never find clear answers so far.

I understand that a "macro" lens is supposed to "uncover details that would be impossible to detect by the eye and give new perspective to extremely minute subjects"(c) Canon.
That is, they are more detail-oriented lenses than non-macro ones.

But, what does it mean, precisely?

To be more specific:

1. What is the difference between a
Canon EF 50mm f/2.5 Macro
and a similar (to me :)) fixed focal length lens such as
Canon EF 50mm f/1.8 (other than the aperture?)

2. Why would you chose a 100mm Macro lens over a 50mm Macro lens? Or vice versa?

3. By reading the minimum focusing distance, it seems to me that all reflex macro lenses have pretty high values (20-30 cm) compared to compact cameras (which I've often placed at 10cm or less from subjects). Interesting. No answer needed here. Just thinking our loud

4. Do you want a low f/ in a Macro, or not? Or, what range would you, ideally want? It would seem to me that being able to properly adjust DOF is crucial in macro photography, as with such small subjects you may have to be quite accurate in deciding what to focus and what to blur, am I correct?

5. Why on Earth is it called "Macro" photography?! All that I know in every discipline tells me it should be called "Micro" photography , but ok, that's the convention, I suppose.

So, thanks everyone for sharing your knowledge and thoughts.