i have to drain out 4800 cusec of water
its the drain line for water to drain
yes
You should install a drain to prevent stagnant water from accumulating and hopefully prevent bacteria such as legionnaire or other water borne diseases and most importantly this drain should empty as an indirect waste as per modern codes
The drain from the washer to the main line is getting plugged and the floor drain is easier. Drain cleaner in the floor drain should take care of it.
I would say that if water had never backed up in your floor drain, then backed up even after you had the drain line snaked, Roto-Rooter didn't do their job. Once a drain line is cleaned, it should drain like it did before the stoppage. As for plugging the floor drain, it is there for a reason, I would not plug it. There are several items manufactured that will allow a floor drain to drain but if the line starts stopping up they will seal the drain off to prevent water from coming out of the drain.
Because both sides of your sink are connected to a common drain line, and the common drain line is slow.
Drain line is clogged.
Yes, be sure to pipe floor drain line properly into water closet piping.
Unless you know that there is one in the line before it gets to the main line, you should. Sewer gas can come up that drain just like any other.
An automatic trap primer works by pumping water into a drain trap. The water is sent from a cold water line in small amounts each time the line runs water. There must be an air gap between the drain water and the fresh water line. The simpler manual trap primer is provided by your usage of the drain. For a seldom used drain pour water into it every few months. A little mineral oil in the drain will slow the evaporation by sealing the water from the room air.
The top hose.
The drain pipe should have a vent that goes up where the sink drain goes into it. That is where it vents. Sinks drain because there is nothing causing a vacuum when the water leaves the sink.