So a D7200 body and macro lens is the best upgrade for me? would I notice the difference going FX?
In a nutshell, the size of your subject will look closer when shot with a DX body vs. FX
providing the distance between the subject and camera is the same. Since the DX body has the crop factor, those bodies benefit macro and telephoto capabilities. If you switch to FX, you could use extension tubes for macro which make the images appear larger on the sensor; however, there is light loss when extension tubes are used....much in the same way there is light loss when teleconverters are used. They can also be used with a DX body to pull the subject in even closer than when they aren't used.
If you are transferring images from camera to Macbook, using a card reader is probably faster and more dependable. But that means doing it manually; however, there is less wear-and-tear on the body. Wifi tends to be used most to transfer images to a smartphone or to use your smartphone to control the body wirelessly.
Have you looked at the Nikon WU-1a Wireless Adapter? It looks like it is compatible with your current D3200.
https://www.nikonusa.com/en/nikon-products/product/wireless/wu-1a-wireless-mobile-adapter.html
The D7200 is a great value in price and most likely will be discontinued when supplies run out. It uses 2 card slots and has some better features that were taken out of the D7500. The D7500 has a slightly better sensor, but overall, the D7200 is more of a workhorse body than the D7500.
If you are looking at FX, the D750 is a stellar body, but since macro and wildlife appear to be your biggest interests, staying with DX might be the better way to go.