You need to prevent all air movement around the line. Consider wrapping it with at least 6 inch fiberglass, over wrapped with plastic sheeting to stop the air. I don't know if that would be sufficient to get along without a heat source. Trouble is, copper is unforgiving to any freeze ups.

I'd check the price of building a ground level addition against the cost of the basement. Remember to factor in the cost of moving the home twice and the space you will lose in the basement for the piers to support the home, and the added footings underneath the basement floor for the piers.

Can you attach a vent line where the pipe exits underneath and run it through the skirting?

Depends on the home. Mine does not have a shut off.

If it is what I am thinking of, it is likely stapled to the back of the counter top. Either remove the counter top to take it off, or use a utility knife to slice it away from the top.

I wouldn't run the siding right down to the ground, frost heave would be more damaging this way. No matter what type of skirting you use, make sure there is provision for adequate venting. Cover the ground with heavy plastic sheeting to reduce moisture. Trapped moisture underneath can destroy floors...

No, the height should not make a difference. I had to raise the vent on my gas water heater to get it above the roof peak to prevent wind from extinguishing the pilot.

does the hutch have an enclosed area underneath it? could be something going on there.

You do need venting underneath, particularly in the warmer months. You can use screens like you have, or there are automatic vents that can be installed. Some vinyl skirting has perforated panels.
You don't want moisture buildup underneath causing mold/rust/rot.

I have the same type of thing going on the front side of mine. The front is almost always in shade, Nothing on the back side, which is always in full sun. It seems to be worse this year, but it has been wetter this year, too. I think it is mold/mildew. I think it will need scrubbing to get it off th...

You need to find a way to make sure things are not stacked directly against the wall so air can circulate there. That being said, i have a closet on an outside wall, and have no problems with it. I do have 6" thick walls, though.

I would think any felt material would only trap water, and make the rust start that much sooner. I just looked out my back window at the neighbor's place. It is an older model from back when they were only 10 ft wide, and the screw heads are rusted, but there are very few minor stains on the aluminu...

Do you have a sprayer at that sink? I had a diverter valve go bad causing low pressure on mine.

Does the fan shut off by itself when the temp drops? I had an older Miller furnace, where there was an opening around the exhaust stack that let hot air down through from the "attic" into the furnace compartment.
On hot days it would be enough to trip a temp switch and turn on the fan.

No, not normal. When mine was set, the installers did an awful job, with some blocks even laid on their sides. Heard a big SPROONNNGGG one night, that was one block shattering, echoing through the I beam. I ordered more blocks and inserted a pier in between each of theirs. Now I have one every 5-6 f...