So the pressure wont bust the pipe.
The pips in a steam heating system need to be insulated to prevent condensation. Condensation can lead to mold and or freezing of the steam pipes in the winter.
In a steam heating system, the pipes transport steam or water vapor to the radiators to heat the building. Insulating the pipes reduces the amount of heat lost to the surrounding environment. Any heat lost in the pipes cannot be used to heat the radiators, and causes the system to be less energy efficient.
Because the ambient temperature on the outside creates alot of condensation and drips, never mind the heat loss of the steam
Internal pipes in a heated house should not freeze. External pipes need to be well insulated from the cold, or they are likely to freeze.
Other wise heat loss will occur and the radiators wont be as hot.
Other wise heat loss will occur and the radiators wont be as hot.
Check your local building codes, but they do not need to be insulated in mild climates. If you experience low temperatures for several months out of the year, it would be best to protect the pipes so that they do not freeze up and cause a clog.\\Not actually insulated BUT if piping is installed over food handling area then provisions a shall be made to place a pan under the piping joints to prevent possible food contamination
If the basement has ventilation to outside, the answer is yes. Heat loss from the pipes will escape outside the house. If the basement is closed to the outside then no, the pipes need not be insulated. Any heat lost from the pipes will provide some heating to the basement that will rise into the house.
You haven't provided enought detail. The answer is maybe. If the sink is indoors and the pipes are in a well insulated portion of the building structure, then probably not. If the pipes are in an exterior wall or in an uninsulated space and the outside air temps go below freezing in the winter, then it's probably a good idea. They'll also be quieter if you wrap them.
To keep heat out/in and the noise down.
the pipes dont need to be replaced, but your condenser should match the system. although, if your pipes are very old, they may be leaky, and new ones would make it more efficient
What ever pipes need to be hit. Especially hard to get to, out of the way pipes that have to be hit fast and hard so other pipes get the message.