yes, unless local codes prohibit it.
The pipe coming off of sump pump that goes outside or if allowable, a drain line.
Yes, the AC drain line may be clogged, leading to water leaking inside the house.
YES, you do need a trap. Usually the bathtub drain is on the same sewer line as the nearby toilet.The smell from the toilet's discharge will sneak up through the bathtub's drain line without a trap ... not pleasant!.
The best way to clean and maintain the air conditioner drain line inside the house is to regularly pour a mixture of vinegar and water down the drain line to prevent clogs and water damage.
Your kitchen sink drain and your shower drain are connected to a common drain line. There is some sort of blockage in the drain line past the point where the shower drain ties in. You need to call a plumber to run a snake through the drain line from the kitchen to where it ties in to the main drain of your house.
This is a job for a qualified plumber, as there are various factors that have to be taken into account which cannot be made.
3" house (building) drain allowable. 4" building sewer line needed for house from sewer main.
The discharge line (soil ) may be slightly back pitched so it takes longer to drain
Hook a Wet/Dry vac (with the filter removed) to the outside drain line. This will allow you to suck the drain line clean and remove any water/algae/debris from the line. As a maintenance item, you may want to pour 1/2 c of household bleach into the drain line downstream of the drip pan to minimize the future growth of algae. Do both of these items yearly to keep problems from recurring.
Yes, the discharge line from the compressor can be hot.Yes, the discharge line from the compressor can be hot.
To put a fishing hook on a fishing line, first thread the line through the eye of the hook. Then, make a loop with the line and pass the hook through the loop. Pull the line tight to secure the hook in place.
The natural gas pipelines run under the house. you can run it from the middle of the house or where the hook up is to the garage for best gas usage.But the line should be outside as much as possible.