I think you really need to do a configuration and that is it.
I tried your problems and I think steps are as follow:
- open terminal in mac
- in the terminal, check you have cmake and ccmake. If not, please type "brew install cmake"
- go to your downloaded opencv folder, make a new folder by typing "mkdir build", then "cd build"
- in this build folder, check you have gcc and g++ installed.
- now, doing configuration by type "ccmake .. -DCMAKE_C_COMPILER=/usr/bin/gcc -DCMAKE_CXX_COMPILER=/usr/bin/g++", type "c" first for configuration then exit by "e" then "g" for generating!
- you should be in terminal again now! then please type "make"
- type "sudo make install", and now the opencv is installed, check it by type "brew list", and you should see the opencv there
- type "brew linkapps"
- do a test if you have python, by typing "import cv", and it should be working!