What size Pipe is this ?
Home Depot does and uses local plumber.
This kit is 1 1/2 PVC.
You can still use this & eliminate the connections for dishwasher & disposal. If you have a double sink, you may have to buy an additional tailpiece for one sink.
If you have a dual sink, then you would just run both sink drains into the one drain.
Believe there will be a plug if there was not a dishwasher connect previously.
Yes
Yes, fits into the knockout plug on the disposal
Everything for a normal install should be included, however there can be exceptions. As with everything, the universal fit, one size fits all, sometimes doesn't. Garbage disposal, most use the same mount to underside of sink. Usually just a matter of loosening and removing existing and installing replacement. Different brand or size may require the drainage pipes to be configured a little different then current install.
Nope.