Servo Control

[mister_e]

to make your back and forth stuff, if your motor don't need much current, it will be easier to use a H-Bridge driver IC like NJM2670 or else.

By using 2 i/o, you'll be able to do it easy...

will look something like this

TRISA = 255 ' set PORTA as input
TRISB=0 ' set PORTB as output

Motor1_a var PORTB.0  
Motor1_b var PORTB.1

PushButtonForward var PORTA.0 ' Push button connected 
PushButtonReverse var PORTA.1 ' between vcc and PIC pin
PushButtonStop Var PORTA.2

PORTB=0

Start:
     If PushButtonForward then 
          Motor1_a = 1
          Motor1_b = 0
     endif

     If PushButtonReverse then
          Motor1_a = 0
          Motor1_b = 1
     endif

     If PushButtonStop then
          Motor1_a = 0
          Motor1_b = 0
     endif

     goto start

to measure the distance you'll have to use rotary encoder, opto devices or something who will provide you some pulses when motor/wheel is turning. By counting those pulse in background (on RA4 pin using internal Timer/Counter module) you'll have some numbers to do your maths

For the speed...it's up to you... some will use PWM, some will vary the voltage accross the motor and probably there's many other way to do it... food for brain cells ;o]