hello. Some Noob questions for you

I will try and answer some of these but in the future you will get better response if you have done some research by looking in the forums here and on other sites and ask specific questions. People will be more likely to respond if they see you doing a bit of work as well.

the "loose" nut is the mechanism that actually raises and allows gravity to lower the extruder one is located on eaach of the two threaded shafts and the x axis assemblies which hold the extruder via the horizontal rods have a fitted hole inside that the "loose"nut should normally be it prevents the nut from rotating along with the threaded rod so as the rod spins the nut will raise or lower on the shaft, lifting or allowing the extruder to move downward. It is loose because as I said it fits into a hole and while in that hole and the rod spins to raise the extruder it actually lifts it by pushing up on the extruder assembly from inside that hole. In the reverse when the rod spins to lower the extruder there is nothing holding it against the extruder gravity actually holds the extruder next to it so as it lowers on the rods gravity lowers the extruder. That is why it is "loose" it is not FIXED in its location. This prevents the printer from breaking it self. if for some reason a request is made for the extruder to be lowered and if the nozzle happens to come in contact with the bed yet the rods are still telling it to go down further the nut being loose simply continues to travel and moves out of its fitted position in the x axis assembly but the extruder simply rest on the bed and nothing gets broken if the nut had been locked in place it would have tried to forcibly keep movin gth enozzle lower and lower and could do damage to the bed, the nozzle and or break ifree from the locked position ruining a big part of the printer, So it is good that it is loose and shold always remain so.

unclog the nozzle is a complex process it is best to avoid clogging it in the first place you can do this by keeping it clean from dirt and also by using a good quality filament also setting the temp to near the max temp can cause things to melt internall and clog things up so the answer will really depend on how it is clogged in the first place.

The cost of the 10cm cube cost is relative to many thing how much infill you are using and the cost of the filament and your print time all have to be weighed together in order to answer this question.

There is no software since the calibration is fairly manual and completely unique to each printer the process can be similar and you can work with individuals or reads things here to find out more about that.

Yes read up on how 3d printers operate there are a few different types but the fundamentals are pretty similar and I would get a good set of basic tools to help you when you get your printer and start printing including:

cricut spatula
calipers
tweezer set (fine tips)
dial indicator
acetone
rubbing alcohol
blue tape
screw drivers
cutters
utility knife
small glass jars with lids (slurry if you choose to go with it)

lead times and arrival in the UK will have to be determined by the ROBO team there a alot of people ahead of you right now I won't even venture a guess on that one.

 

I can't just leave that one...

all 10cm cubes must be PRINTED SOLID