Hi Ted,
1. Are there any buildings, tress or any obstacles in between the Aps as this will reduce the distance. Line of sight is preferred. With an E500 for example up to 200 meters should be possible.
2. 50% +
3. Yes you can.
4. Mesh is a good tool to have but I wouldn't recommend building an entire wireless network with it. If you're meshing 1 or 2 AP's that may be OK (depending on throughput requirements). However if you’re looking at more than this then there are better solutions, have a look at the PTP & PTMP solutions from Cambium.
Further reading: