Heya,
It is probably possible to run a minimal reprap off one arduino, but that would really be pushing it. The best bet for the long-run is to run the cartesian bot one one arduino, and any extruders on the 2nd arduino. it gives us room to grow, and allows us to keep the cartesian bot code simple, as well as the extruder code simple.
Pretty much any arduino will work, as long as it has an atmega168 chip in it. any of the newer ones such as the diecimilia will work.
personally, i'd recommend the boarduino that ladyada sells. you have to solder it yourself, but its alot cheaper ($15), it fits nicely on a breadboard, and i think i'm going to eventually make some sort of breakout PCB that the boarduino will be able to fit into that will supply all the pins, nicely labeled to plug the rest of the boards into.
here's the link: [
www.adafruit.com]
as for shields or special cables, not really. i've been using solid core ethernet cables, for pretty much everything. it contains 8 wires, each with a different color, is easy to cut to length, make into cables, etc. not to plug the RRRF, but we sell it by the foot for dirt: [
store.rrrf.org]
if you get the boarduino, you'll need a special cable to program it, but you can use it for all boarduinos (and some other arduino variants) its one of the reasons why its so cheap... the serial chip has been pushed offboard.
i'll post a picture here in a little bit of my setup, but i've been bolting all my boards to a thin sheet of plywood.... it really makes things alot tidier, and allows me to put things away without having to disconnect every single board.
