The Fab@Home people have already done a few embedded circuits by printing with conductive silicone. Making circuitry will be a very important ability for these machines.
Are there plans to modify the current design to replace non-reproducible parts such as bolts with parts that can be manufactured on the machine itself, bringing the overall RepRap design closer to 100 per cent self-reproduction?
Yes - that is definitely one of the evolutionary paths to greater reproductive success. For the immediate future I will be concentrating on widening the list of materials that RepRap can build with (starting with electrical conductors). That widening will implicitly raise the proportion of parts that it can make for itself, of course.
This is the first time I've ever heard anybody advocate for putting stuff INTO landfills as an environmental measure. An interesting approach to carbon sequestration.
Can the RepRap recycle what it manufactures?
Yes, recycling has been built in from the start... The main plastic we are using is polylactic acid...
But I want to move to using a non-biodegradable resin. This too is sourced from biomass, but is stable in the ground. That means that the more reprapped goods that get made from it and thrown in landfill, the more carbon is taken out of the atmosphere and locked away for good. And, in 200 years when we have taken so much carbon out of the air to make stuff that anthropogenic global cooling is starting to be a problem, the landfill sites become our strip coal mines to save us.