Introduction and a few problems

Looks like you loaded a configuration.h file with the default max extruder temperature which is 240C. The original J Head extruder that came with the Kickstarter Robo3D should not be heated over 240C or a PTFE sleeve in it could melt or deform. I'm not sure if that is the case with your J Head but I would make sure before you override that max. When you change the extruder to an E3D you can change it to something over 300C like this around line 159 in the configuration.h file:

// When temperature exceeds max temp, your heater will be switched off.
// This feature exists to protect your hotend from overheating accidentally, but *NOT* from thermistor short/failure!
// You should use MINTEMP for thermistor short/failure protection.
//#define HEATER_0_MAXTEMP 240 //Original robo3D setting
// SLC change for E3D hotend
#define HEATER_0_MAXTEMP 310​

The XXL LCD works great. I have not used a USB connection since I got one. Even with USB 2.0 a print driven with USB can have layer quality issues that are modulated by activity on the PC. This was on a pretty fast I7 laptop. I have not seen this since changing to the SD card on the LCD.

That's funny, $18 shipping from US where that other one was $2.60 to US from Israel.

 

I suggest adding a few extra layers of washers to tighten up the filament guide springs. I think I added 3 or 4 to each side.

Also if your filament guide does not have a thumb tab (the newer printers might) try this one:
http://forums.robo3dprinter.com/index.php?threads/better-hobbed-bolt.846/page-6#post-22171