It's good that you're getting the kids involved in the build process.
I'm not sure how to help with 1. other than to point you at this post, which may help:
http://forum.seemecnc.com/viewtopic.php ... ifi#p78035
2. Octoprint was one solution to printing away from a larger computer, which many people didn't see a need for (It also gave you web-cam support, but a Nest Cam is easier these days by far). Others, like printing from an SD card, using duet, or running a BBB based solution with the slicer installed on the controller itself also exist, which means it wasn't something everyone was going for. It also, as you noticed, has some 'fun' teething troubles.
3. Not as far as I know, but then, many people run in stealth mode, and it may work OK, so no one ever asked for help about it.
4. The Rambo is a capable, but basic controller (at least given the proliferation of solutions like the Duet, Smoothieboard, and Replicape, which manage to pack surprisingly excellent hardware into a nice price point, when it came along it was a nice improvement in quality of life over the RAMPS board). It has some issues with the extra overhead of delta kinematics, but does OK. I've not replaced mine yet, but I have been looking into it. My evaluation of those I've looked at is below, but be aware, I haven't used any yet, nor am I a real guru (626 for Smoothie, and Mike for the Duet are the people to talk to.)
Smoothie family:
-Excellent software, with a branch designed for delta calibration.
-Hardware is more than capable, but somewhat memory constrained in the current version.
-Is designed to support other tools such as laser cutters and mills, and has some level of documentation for that.
-Thermocouple, but not PT100 support, gives it potential high temperature capacity, but does not goes as high as it could, and uses a slightly less convenient sensor (I don't like using anything but PT100s, since I can just pop them in and out with a setscrew, and not worry at all). The main developers are uninterested in PT100 support. (They have been asked)
- The V2 is due out at some point, and has multiple versions, all of which are a boost on the processor, but the code is also getting significantly refactored.
-Has some glitches due to bone-headed mistakes on the part of some slicer developers. (single micron moves need not apply).
- A variety of boards support it
-SD card acts a bit weird, and access is somewhat odd. Flakey even at times, due to the SD card being considered to be mounted by two different file-systems when connected (Or something. I'm a machinist, not a programmer (Or at least, not that kind of programmer. I write in G, not C))
-has had a few QC slip-ups in the past, but none noted recently.
Duet:
-Very excellent calibration and delta support.
-Very usable interface in general, and web in specific.
-Segmentless delta kinematics make more accurate, better looking parts.
-Supports a touchscreen interface with very little overhead. (and you can pick one you like)
-Thermocouple, but no PT100 support. Developers have not to my knowledge discounted PT100 support.
Replicape:
-Very powerful hardware.
-Only basic delta support, but firmware is in active development.
-No need for 24-12V stepdown converters for fans/lights or steppers, as one is built in for the lights/fans, and the stepper drivers handle 24V well.
-Cheap price (Lower than the Rambo)
-PT100 support in on the table, and Thermocouples are workable.
-One-wire low temp sensors (sub 100 C really) can be connected to monitor temperatures, for additional data and control.
-Can run slicer and other things on board
-Connectable to displays via standard cables (HDMI), and can be attached to a very nice touch screen (The Manga screen was developed by the same fellow)
-1/256 programmable microstepping, in addition to other modes are available.
-stepper drivers are as quiet as you are likely to find.
-Original boards have the Reach for expansion, the Rev B is potentially getting one as well.
I am currently torn as to which controller. Both the Duet and Smoothie work very well. The Replicape has immense potential, and is being worked on fairly actively. But the Rambo works OK, so long as you don't get unlucky on the calibration front (Which is what minions... Err, kids, are for). Give it a try with the Rambo for a while, and then decide what's important to you. And the longer you wait, the better your options get.
)
