1) Inside your steam folder will be a folder for Avorion. And inside that, a scripts folder.
Should look something like: C:\Program Files (x86)\Steam\steamapps\common\Avorion\data\scripts
2) All the scripts are written in lua. You can edit them with any text editor including plain old notepad.
3) This forum should suffice.
If you are having this much trouble simply importing ship designs, you will undoubtedly find modding to be very tricky, to the point of not possible. Not anytime soon at least.
I am confused how does not knowing what file ship designs are indexed under mean that I will not be presumed to have and aptitude for learning about mods? I only ask because your statement following you answers comes across condescending.