2" minimum.
Most of the time it is 4 inch.
Depends on the mateiral you already have (PVC) Galvanized nippe and brass P trap or rough brass connectiong to the trap and then of course what size of drain basin, KS, Slop Sink
Could be a drain for the inducer motor if it has one and it depends do you have a a/c coil on your furnace if so it could be a drain for it.
Abs to PVC glue sold at home depot Color it aqua blue/green plumbers key term. GUMBY GLUE Depends upon what you mean by "black pipe". If you mean ABS drain pipe, there is glue for that. If you mean steel "black pipe", i.e., non-galvanized, then you would need a threaded connection adapted to the PVC (either a female PVC connector on a male black pipe or a male PVC connector into a female black pipe fitting). The secondary question would be, "Why would anyone want do to that?"
I can't imagine the plumber only giving 1 year on the PVC. Cast iron is rough on the inside and those rought spots can snag paper, lint, etc, eventually leading to blockage. PVC should last much longer and be less susceptible to blockages from material getting caught on the inside wall of the pipes. Also, PVC doesn't rust, while cast iron will. All-in-all, I'd have to vote for the PVC (make sure that it is at least Schedule 40 PVC).
no 2" is enough if it's just the washing machine.
Yes, if they are the proper size to mate, or match up. yes
Most of the time it is 4 inch.
If the toilet and shower are in an upper floor then there is a PVC drain for both that will drain to either the sewer or septic. If there is a vertical piece to this, as there is in my basement, then you actually get some dribbling and running sounds from the water 'falling' down that vertical PVC. I get this same noise from the washing machine on the main floor draining down to the basement.
Probably the wrong size flange. Is the flange a toilet collar? If so the pipe is probably 4 inch.
Yes
Use PVC for the drain line. It does not require insulation.
Yes, but PVC creates problems
Depends on the mateiral you already have (PVC) Galvanized nippe and brass P trap or rough brass connectiong to the trap and then of course what size of drain basin, KS, Slop Sink
Basement, if any, will oft times have PVC piping used for drain lines in it, if codes allow PVC piping.
none
PVC pipe is not affected by acid. Why would you pour acid down your drain in the first place? It will not cure any problem you have.