Raise it, or get a plumber to do so
Yes, a sewage drain pipe can be too large.
To prevent water damage from a sink overflow drain in your kitchen, regularly check and clean the drain to ensure it is not clogged. Install a sink overflow alarm that alerts you when water levels are too high. Additionally, consider installing a secondary drain or overflow pipe to divert excess water away from the sink.
Probably the wrong size flange. Is the flange a toilet collar? If so the pipe is probably 4 inch.
Install a ty fitting on the stack in the basement then run it to the sink. Put it low enough to account for a fall in the pipe, to allow proper drainage. Be sure to install a waste and vent pipe to code for both fixtures.
Waste water will run away too quickly to properly carry away any solids in drain pipe, eventually causing a clog.
Ingested drain cleaner is a corrossive substance do not induce vomiting.Acidity is high.
The toilet may flush but the water doesn't go down if there is a clog in the drain pipe or if the water level in the tank is too low to create enough force to push the water down.
1 1/2" or 2". Depends on your pipe size on the trap arm. 1 1/4" is too small for a kitchen sink and not allowed.
First thing you should do is call a plumber. Drain lines are not supposed to leak. Your drain line is clogged and needs to be snaked out and the leaking pipe repaired.
Depending on the type of drain pipe referred to, "Yes", it can have too much drop or "fall". Specifically sewer drains, as too much drop allows the liquids to leave the solid material behind, causing a blockage. The water outruns the solids.
Extend the overflow pipe underground to a point where it is above ground.
The toilet bowl water level may be too high due to a clog in the drain pipe, a malfunctioning fill valve, or a problem with the float mechanism.