The farthest are 8 7/8 inches apart at center of hole. The top ones are 3 1/2 inches apart.
There are 5 holes for mounting screws. They are approximately 2" apart on an elliptical pattern.
My house is in cement and I used a type of screw that does not need expansion (blue tapcon), which measures 3/16 diam and 1 1/2 long. You need a drill to make the hole. I don't remember the size of the bit. It was easy to install.
This one can hold 50 pounds
Unfortunately, no. If I had known this I would never have bought it! Charge a few more dollars and ad the hardware, it would have helped me immensely.
The outer one's are 8 7/8 apart. You might be able to drill the slots a little larger to use the existing holes.
I used 3/16 concrete tapcons 2" lomg