relays needed for auto door actuators?

The second switch will wire in parallel across the other switches wires. Basically you are having one or the other switch throw power or ground to the relay to activate it which in turn activates the actuator.

As far as having a second switch inside to pop or open the doors try very hard to add a mechanical handle inside. I redid a 56 Chevy and the upholstery shop added door pop actuators and an inside button but after going over some things with the owner of the car I designed an inside mechanical release. Should you ever be driving down the road or even stopped and there is a major electrical problem on a vehicle equipped with electric door poppers there is no way to get out of it without climbing out the window. Now add in a vehicle with power windows and you are stuck inside.

Below are some links with pictures of the ones I made for the 56. Basically it was an inside hood release handle from a Toyota, some bicycle cables, some cable adjusters to take out slack when the cables stretch from normal use, some pulleys and some fabrication.

http://rides.webshots.com/album/113373496zNgIvF?start=12

http://rides.webshots.com/album/113373496zNgIvF?start=24

Think safety also with the install.

Jim