It may clean out some clogged materials, but in general , household drain cleaner is junk that should be avoided. You achieve more by mechanical cleaning with augers and rods.
It is not recommended to use bleach or drain cleaner in garbage disposals. the chemicals can cause corrosion and can splash up, causing damage to counter areas and nearby persons. It is best to follow your disposal's instructions for cleaning and remove and clear the j-trap of the sink instead.
yes
The sink drain is blocked somewhere after the disposal. take apart and clean or renew sink drain.
As long as the drain basket for the disposal will fit the drain hole in the sink, there shouldn't be a problem
garbage disposal
The disposal has to be in place so that the drain on the dishwasher is connected. If you do not have a disposal or are removing it, there is a extension tube for the drain that has the dishwasher tube in it. The disposal does not have to work for the dishwasher to drain. The water is run through the disposal so that any food particles get ground before going in the drain. After a while, the disposal will begin to smell if it is not run.
If it goes into a garbage disposal, the disposal needs cleaning. If it goes into a tube in the sink drain, check that for plugs. Is the drain hose open all the way, no kinks?
If the sink/sink drain fitting connection, sink drain fitting/disposal connection, dishwasher/disposal connection, disposal/drain elbow connection are what are leaking they can either be tightened or have gaskets replaced or other sealing methods used. If the disposal is leaking elsewhere the disposal needs replacement.
It possibly has garbage trapped in parts of it or the tube right below. Fill the sink with hot water and drain it through.
Same as you would for a double sink. There is a short tail piece with the disposal that attaches with a flat plate and a short bolt. Install the disposal on the sink and route the drain as needed. There has to be a trap between the disposal and the drain.
You put waste food and vegetable products into them and the macerate it and flush it down the drain.
Garbage disposal, if one is installed, or a wye branch fitting on the tail piece of sink drain. Dishwasher drain line should have an air break or air gap before the disposal or wye branch fitting.