Yes, there’s a link cable example, which is called “30. Serial.gbb”.
Of course.
It supports string partially, i.e. print "pi=%d", 22/7 and label #0 "hello", the string are constant literals, this is enough for text representation. As a constrained platform, gb is not very good at dynamic allocating, so it doesn’t support assigning string to variable, concating, etc.
Actually the runtime part is based on the GBVM project, their capability are quite similar.