"Friendship" and "hostility" refer to the present relations between Justinian and the Goths and what they may become.
Amalasountha.
The correspondence between Queen Amalasountha and Justinian is given in V. iii. 17.
In Latin serica, "silk," as coming from the Chinese (Seres).
Cf. Thucydides' description of the huts in which the Athenians lived during the great plague.