About homing and switches...

[routercnc]

To use one sensor and two targets... Arent the sensor pointing towards one of them, how can you make it work in two directions?

Imagine the sensor is mounted to the gantry and pointing down. It moves sideways over the target, not directly towards it. At some point when it is directly overhead it will trigger and stop the axis. If there is a fault it will just glide on past without damage until the gantry hits the hard stop further along.
When it is moving the other way, again it is looking down and will eventually glide over the target at the other end which will trigger the axis to stop. So one sensor, two targets.

It has been shown to be just as effective using a parallel approach as a direct approach. As long the target gets within 4mm (or whatever the rating is) it will trigger no matter how it got there.