With a compression mission ring
By cutting in a cast iron Wye so the flow enters the sewer line (soil pipe) at a right angle
This can be a complicated job as the toilet drain ranges from 3" -4" and a variety of materials from Plastic to cast iron to galvanized. Then there is the venting to consider and NO a shower drain CANNOT be used for a toilet discharge as the shower drain is normally 2" diameter
Yes, it is done all the time
The shower may be leaking from: 1) A failure of the drain and associated piping itself (e.g., corrosion of the cast iron floor drain), 2) A failure of the shower pan, which is an ostensibly waterproof liner (may be metal or synthetic polymer) embedded in the tile floor (or comprising the plastic floor) which is mechanically connected to the drain; or 3) Leakage of water in the shower's surrounding area (walls, non-pan floor area, etc.) which is accumulating and dripping near the drain.
Where? What is your question?
from the hub to the spigot
You remove the existing tub shoe and related fittings and install a new assembly. In some cases a reciprocating saw will be needed to cut the shoe flange located inside the tub
Galvanized pipe for water and drain lines. Cast iron pipe for main drain lines.
Both and but normally a master plumber would fix the problem by removing the existing drain lead/copper /cast iron and install a new drain and remove the membrane to the existing slab water proof the slab with either roof cement or flashing cement then install 4 PSF sheet lead over the drain flange/clamping gravel stop collar and you will now have a leak proof job
Yes, but PVC creates problems
If it is "rusted out" you do not repair it, You do replace it with XHCI
You can buy the new cast iron flanges, with the expandable O rings that push into the pipe or you'll have to do the old style or pouring lead onto a cast iron flange. The latter option should only be done by professionals.