Try the macro lens first. Focal length doesn't have the same importance in macro shooting as in regular shooting. Perspective and framing are usually not significant factors. Working distance and lighting are. If the 100mm does not approach the subject too closely and if it allows the lighting you need, then I think it will work great.
The zoom will give weird results with extension tubes. It's because the marked focal lengths of the lens change when focusing. That impacts the effect of the extension tubes. It may be tricky to get the magnification you want.
You might find it hard to do macro on a tripod unless you have a focusing rail. You will need to move either the tripod or the subject small distances to achieve focus. This gets harder the higher the magnification. With flash, you won't need a tripod to freeze motion. Hand-holding with a flash might be better unless you need precise framing or are doing focus stacking. For that, use a tripod, but then you will need the rail.
I find for macro outdoors, it is way more practical to hand-hold. If you do this, the 70-200mm will get heavy fast.
Lighting can be quite a challenge in macro, depending on the magnification. (Everything gets harder as you go to higher m.) Tons have been written on the Web and here at POTN on flash diffusers for macro photography. Do a little search to see what might be suitable for you.
You have the lenses, so I suggest you do some trials to get some experience and see what issues you encounter.
