Servo motor control

Hi, I want to create a servo controlled unit which can control opening and closing of the sliding doors automatically. I have never used or bought a servo motor before so I will need all the help I can for this project. I would like to know:
1) Which kind of servo motor can I use for this project?
2) I saw few servos on internet and they have different number of wires comming out from them, i.e. some have 3 wires and some upto 8. What is the difference?
3) Any suggestions on how to control it using PIC & which PIC would be suitable?
4) I have noticed at few building having this kind of system, the doors slide slowly when opening and closing towards the end i.e. near to when they are fully open or close. How is that achieved?
I will buy one servo based on the answers and begin my project accordingly. I appreciate all the help in advance. Thanks

Lots of things to consider...

First, a servo is just a motor with position feedback, the feed back circuit will keep the motor or move the motor to a "position". The feedback circuit can be in the motor housing or not.

Stepper motors will also have 4,6,8 wires. Are you looking at servos or steppers?

But for your project you do not need either one. A "regular" motor will do if all you want is full open or full close. A sensor, limit switch at each end will work for feed back.

Then you need to know the torque required to move the door is a worst case scenario. Wear and dirt will change things.

Simple relays will work between the PIC and motor for control, how many amps? The PIC can be most any of them but we will need to count I/Os. Still a few things to add...

Lets assume a DC gear motor for torque and speed. The motor can be turned on and off and direction control through the relays and a PWM can be sent through the relays with a mosfet or IBGT for speed control.

You may also want a sensor to check for obstructions when the door is near closed.

A magnetic switch can be used for door position also. One could be place near full open/close to toggle a pin for speed change. PWM changes.

Sorry for not giving direct answers, but there are many things to consider for the total design.

To be honest, you don't even need a PIC for this type of project. Press a button to open the door, this latches and powers a standard motor, with say a rack and pinion system to move the door. At the end of the track a simple switch un-latches the switch and the motor stops. Same could then go for the closing of the door.

One area where a PIC would be useful, would be for sensors to detect if something has jammed the door, or if it was closing and someone was in the way (such as the IR detection on lift doors)

I would like to have a microwave sensor to detect the movement around the door, and an IR sensor to sense if someone stood still between the doors. I just bought one sensor HB100 (DATASHEET ATTACHED), I am know I am being a little sidetracked from the original problem but I think it will be good to start from here then gradually coming back to the door opening & closing mechanism.
So, this sensor has an IF Output, has anyone seen or got any circuit where this sensor can be attached to a PIC. I have tried a lot but can't find anything online to integrate it with a PIC.