pan-tilt-dolly project. just starting.

Hello u all.
I m new to the forum, and also newcomer to DIY MoCo... So many noobi questions, doubts etc. And apologize for my english.
Thanks in advance for the open MoCo community. Great stuff all over the place!!!

first of all, a thing to consider, I live in argentina so is very complicated to get things, import them etc. Also i get paid in pesos (4 pesos=1u$ dollar) so for us everything is very expensive to....whatever...

So.
I would like to build a Motion control and Time lapse system.
To Start, with pan-tilt-dolly. For the future would be nice to add roll and focus puller option.
The camera will be a Canon 5d Mark II.

The main use will be studio, but i would like to be able to to take it outside with a laptop.
Repeatability is important.

Hardware.
This is what i already have.

1 Servocity PT-2100 pan and tilt head.
1 Arduino Mega
2 Stepper Driver v2.3 Fully Assembled (makerbot) will this work????? If, i need a 3 one.
3 NEMA 17 Stepper Motor. Holding torque: 260mM*m, 200 steps per revolution (1.8 deg/step)

For the dolly i have found a distributor in argentina of Igus. They are not answering the phones...but will see.
Look very nice, and i will do it 2000 long.

Configuration: DryLin® W – Carriage, mounted
Shaft diameter (mm):20
Rail width (mm):80
Length of complete carriage (mm):200
No. of carriages:1
Rail length (mm):2000
Manual clamping :No
Rail options:
Standard bores
Price:
Upon request

The head weighs 3.8 Kg + the camera and lens 1.5 Kg + Extras 1.5 Kg = Almost 8 KG. What tork do i need? What motor will meet my needs? What i have is good enough ?

Software.

I'm thinking that i would like to a have a integrated system. DMX lighting, Motion control, and camera control. Be able to record and playback movements , fine tuning etc. I think thats possible with Dragon Stop Motion witch i don't own. May be Max/msp or Isadora ... To communicate with arduino.. make a UI, and to be able to use some kind of remote control.. Wii, iphone (OSC), or custom made joystick..

I know is a lot of work and many things are beyond my skills... but there is another way to learn? and what are friends for???..

Many many thanks in advance..
Alejo Yael.