CNC newbie needs help

[jnymarkp]

Hi CNC'ers

I am a total newbie into CNC, but have fallen in love with this topic.
So i have been lurking around CNCZone for several month now trying to decide on what to build.
I just amazed of what people are building in here!

Ive ended up deciding for an gantry style mill with fixed gantry and moving table. Mayby later adding axis 4 and 5.
Tablesize around 60x30cm. Z clearence 35cm (planning for axis 4 and 5 and automatic tool changer in due time).

The primary goal is to be able to machine parts for RC vehicles, e.g. tires, hydraulic parts (valves, pistons. pumps etc.), so i want to be able to work in everything from rubber and wood to aluminium and even steel.

Unfortunately i don't have the tools to do any steel machining, så my plan so far is to build a CNC mill out of MDF. Then use this machine to fabricate aluminium parts that can be used in a new and stronger setup.

I have set up a Ubuntu desktop and installed EMC2, and have been looking at gCAD3D as CAD software.

But for the last weeks i have been stuck and don't now where to go.
So here i go with a few questions just to get me started.

1. What size of stepmotors would be needed to be able to do milling in aluminium and steel (size as in oz-in / kg-cm)?

2. Can i build my own drivers running the motors at half step, or should i buy prebuild drivers with microstepping capabilities?

3. What kind of guides should i use?
It seems i can choose from either steel rod, linear rail og supported rail.
I have found some complete sets of supported rails for a 3-axis mill, but are they strong enough for what I wanna do?
Below item includes SBR-20 linear rails and RM1605 ballscrews.
Example: cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=250533252129

4. What sort of motor is required for the spindel (DC/AC/servo)?
If I also want to be able to use the mill as a lathe (inspired by Mill2Lathe on youtube.com/watch?v=7Mqy0CRu5rY).

Please forgive me if this is the wrong place to post this.

Thanks in advance!

Jesper