Greetings from freezing Melbourne everyone!

I'm new here and making my first foray into DIY CNC. The young master is now getting to an age where taking things apart to see how they work is a full-time hobby and he's renewed my interest in all things electronic and mechanical. These days universities offer an array of courses in robotics and mechatronics which didn't exist when I was a student, so I'm looking to become something of a mentor for my son; enabling both of us perhaps, but with the best intentions.

History? I educated in Electronic and Computer Systems Engineering in the nineties, then immediately moved into the I.T. industry, so my skills in 'hard core' engineering are more than a little rusty. But, I've brushed up on some electronics and familiarised myself with some relatively recent Arduino inovations with a view to building a few projects which my son and I can both use. It's already been great fun, but to the point...

Suffering a life-long desire to have access to a CNC mill or router, it's suddenly the perfect time to build one. Some basics I've already decided on; 400mm x 400mm x 100mm work volume, softish materials (plastic, wood, fibreglass, some aluminium), small 700W Makita router (it's a multi-function device, not a dedicated spindle), air cooling only, low power requirements, lightweight build materials so it can be portable, must fit on a deep desk (700mm), reasonably quite, can accept cutters from 1/2" down to sub-millimeter for PCB prototyping, can be fully enclosed possibly with dust extraction down the track.
I have a few items on the way already, like an Arduino CNC shield and driver carriers, four low-current Nema 23 steppers, basic 8mm lead screws and associated bits, some aluminium v-slot sections and delrin wheels for linear motion, but much of the small hardware and structure are as yet unconsidered.

So, that's me, I suppose I'll see you 'round. I'll leave you with a couple of the questions that I have in mind, so perhaps you good folks might direct me to the appropriate subforum to ask them?

Dave.

Questions:
1) Maybe I've not looked hard enough, but I don't see any CNC router designs which can be mounted directly to a flat work piece, as opposed to mounting the work piece on a CNC router bed. Is there such a thing as a 'bedless CNC router'? Imagine, if you will, a core-xy style system which can be mounted to a large panel to route logos or inlays. Exists?
2) I often wonder at the shape of gantry uprights on many designs, the familiar 'foot' shape, presumably to balance the bearing loads front-to-back in the y-axis. Particularly in DIY designs the spindle/z-axis seems to be hanging waaaay out in front of the x-axis. So, why are more people not balancing the z-axis components across the gantry instead? Ideally the x-axis bearing centre, the z-axis centre of mass and the lead screw should all exist on the same plane, right? Yet, almost everyone seems to insert the z-axis motion components between the x and spindle,unbalancing the gantry. Why not move the linear parts of the z to the back of the gantry with a wrap around design, or better yet built a horizontal gantry with a slot and install the spindle right in the centre?