Suitable for a cnc mill ?

I’m now very eager to start my first project. But as many funds are tight so i've set my self a few goals to achieve this being my first build and have very limited knowledge on cnc In general
My goals in priority are as follows
1. To keep the other all cost of the project to a bare minimum e.g. purchasing second hand from eBay and DIY’ing as many parts possible.
2. Keeping it simple as possible due to me lack of experience I don’t want to take on something far beyond my skills and just get bogged down struggle and loose enjoyment and interest half may through
3. Reliable don’t want to go down the route of having loads of steps lost and having to hover other the machine whilst in operation due to poor quality Chinese electrics “unless I cant afford to do anything other
4. deep cuts I would like to achieve depths of 40-50mm so when building this machine rigidity to avoid the machine flexing under such stress’s will require some thought
5. bed size I’m hoping to achieve a size great the 150 x 305mm of working area and about 150mm rise and fall “but I would give or take a inch or so on those dims”

All that aside I’ve got a chance of acquiring this machine it looks very sturdy and I think the name say quite a lot on its build quality but I’m unsure on mounting the vertical stepper movement to it as I’ve got no idea how the stepper would know if it had moved a mm or 10 or 100. Please have a look at the images and let me know what you think.
Jase.
http://inlinethumb16.webshots.com/44...425x425Q85.jpg
http://inlinethumb49.webshots.com/43...425x425Q85.jpg
http://inlinethumb40.webshots.com/48...425x425Q85.jpg
http://inlinethumb26.webshots.com/46...425x425Q85.jpg