Packie is the most similar to Niko though thinking back on it, but I question if that's because of true friendship or convenience. Although there is some bonding on the friendship missions between him and Packie, namely how Niko can relate to having an abusive father. Most of the early Packie missions were also fairly pointless compared to the other mission NPCs, but there was also the need for money (despite how meager it is) and it led up to the more important missions. After that all of the interaction with Packie was pretty minimal as far as I remember.
True, although from the standpoint of the PC, choosing Kate to die is the inferior choice seeing as Roman's taxi service is the shit and Kate won't even put out.
