Delay for Linear Actuator for Van Doors

Hi, this is my first post so I hope I don't sound too dumb, I'm trying to convert my side barn doors on my wheelchair lift van into automatic doors using linear actuators and a remote kit. This would make it much easier to close the doors after the lift gate is closed and I'm already in the van. My questions are about setting up a delay for the actuators so one door will start to open about two seconds before the other, then the opposite door would start to close about a second or two before the other.
My next question would be the easiest way to add remote switches outside the van in case my remote control batteries die. I will be mounting the remote control box inside the van in an easy to access location from somewhere near where my wheelchair will be tied down. Is it just a simple matter of a couple diodes to prevent any back feeding and tapping into the wires going to the actuators? Or is there a remote control box that already has this feature so I could control the doors from two separate locations with manual mode in case my remote batteries die? Thank you for any help or direction.

Do the actuators have internal limit switches?

If I interpreted it right the limit switches were part of the remote control receiver / control box. I didn't purchase anything for this project yet. I'm a little weird I guess, I like to know exactly how everything is going to work and be wired before I buy stuff. I'm hoping to do it once right and be happy with the results. But I am open to suggestions on actuators, switches, controls etc.