Old galvanized pipes have a finite lifespan. If you repair this leak, you have a good chance of it developing another leak in another location. The only good solution is a complete pipe replacement. The major expense of a pipe replacement will involve the digging of the trench from the meter to the house. This is an area where a DIYer can save some money. Have the utilities companies come out and mark the location of the pipe and any other utilities going to the home. Then you can choose a route parallel to the current pipe but just far enough away from it that you aren't disturbing it. You can rent a trencher (Maybe $200) and hand dig the larger access points at the meter and house. Then you can call a plumber to lay the pipe and make the connections. If you are not physically capable of doing this, then do you have any family or friends that would be? Church group? Scout troop? There are usually community resources that can help you to figure out what you can do here. The worst thing you can do is to ignore the leak.

Novice, condensation on cold water pipes can be a very serious problem. It is particularly ornery in humid environments, which might include your kitchen. We had to wrap steel and copper pipes with insulating material to prevent this in our basement, and I've even seen pipes that feed fire sprinkler systems do this to the point of damaging the ceiling directly beneath them. You might beg, borrow, or buy a dehumidifier and run it for a short time in your kitchen to see how much it collects and also to see whether it stops the drip from your pipes. Your plumber who suggested keeping the ceiling open was doing you a favor, I think. The fact that the drips are not constant suggests condensation. After all, a pipe has fairly constant pressure on it, and a hole is a hole. If the moisture comes and goes I'd argue "condensation" because the moisture content of your kitchen can vary a great deal (are you grilling outside some days and boiling pasta in the kitchen on others, for example.) Notice: I ain't a professional and YMMV. Good luck, M

The requirement to add a second 'made' electrode to the grounding electrode system was added a while ago (might be ~21 years). All electric work is normally grandfathered to the code in effect when installed and inspected (if it was not we would be forever tearing houses apart to upgrade old stuff every 3 years). Some exceptions are made for things like GFCI kitchen counter receptacles and bathroom receptacles in many areas that require upgrades if ANY work is done, or of the property is sold. Knob & tube is still in the code. The 5 foot requirement (you must hook to the water line within 5 feet of entry) is even newer. To many times the pipe was used as a conductor all the way across the house. It is very worthwhile to have at good grounding electrode conductor and the correct clamp, even if you only have a single electrode. The rod provides protection from lightening, leakage in the pole transformer, and a solid earth connection in the even a high voltage transmission line ever comes in contact with the 120/240 V conductors. This is more common than you would think if a HV line breaks and falls. They often strike the low voltage lines below them on the pole before hitting the earth.

Penetrations through the floor of a multi-floor building should be fire and water resistant. You can learn about specialized products you can use here: https://www.3m.com/3M/en_US/building-construction-us/applications/firestop/