CLamb

Two sections of cast iron sewer pipe in my home need to be replaced due to cracking and splitting from a masonry support shifting. Immediately upstream is a T that goes up to the bathroom sink and vent and continues to the WC. I intend to repair it with PVC. The home was build circa 1950. I certainly don't want to replace any of the upstream piping. Should I replace all the downstream cast iron piping while I'm at it? It seems to be in good shape but is part of a tangle due to modifications over the years. If I just replace the two lengths I must fit the PVC into a cast iron hub. Do I use a donut or caulking? I'm am afraid of putting much downward pressure on the pipe with the hub to force the PVC into it. On the upstream end I will have to put in a new hanger on the end of a T. How do I fasten the hanger between the two joists? Originally there was a piece of wood put between the two joists to which the hanger is attached. I don't see how this piece was fastened in place. I could toenail another piece but I'm not sure that will be strong enough. You can find a set of pictures here http://home.comcast.net/~cplamb/piping/pictures.htm