What does tom do when he can not climb the lightning rod?
Any attempts to modify an existing gas furnace system that was not designed for heat recovery will result in either or both of the two conditions:  substandard heating temperature and/or air flow in the areas served, and/or  a condensing of the flue gas which will destroy the system and venting system. I don't think there is an effective and more importantly safe way to do this without compromising safety of you and the other residents or severely impacting the performance of the existing system. Having them duct you a supply and return vent would probably be best, but again they will lose performance upstairs unless modifications are made to the existing unit (unless it is oversized to begin with). Sorry for the bad news, but a few degrees of heat is not worth creating an unsafe condition for you or the people above. Your idea of thermal mass is good though, although I wouldn't use water jugs due to plastic fire hazard. Large, heavy metal objects placed in front of your electric heaters will absorb heat and continue to stay warm when the heaters have cycled off. Good luck,
static ip address are set by your ISP .. LAN ip's are set in the tcpip settings of your network adapter your notion that you can not plug a hard drive in to a newer pc and have it boot is 100% wrong . true it may not have the correct drivers to run correct BUT IT WILL BOOT do it all the time . to recover media to boot: if it is a sata hard drive . in the bios . change the drive from sata to ahci if IDE move jumper to select and boot in safe mode as for the IP , there is no registry chain . the LAN ip ( tcpip settings) is all your going to need , because any port forwards to the host are going to be set in the router the client trying to connect simply no longer sees the correct LAN ip