Answers

Probably need to have the skylight reflashed.  Skylights need to have special flashing kits designed for skylights.  Have a professional come to inspect to see if you have a curb mount or deck mount skylight and they will be able to give you a price to replace your current flashing with a new airtight skylight flashing kit.

I would recommend contacting the company that installed the water heater

Yes, you need to contact a roofing company to check it out.  Possibly need a rain diviter installed.  Possibly need a gutter installation company to swap out current gutters for larger commercial size gutters.

We just had sod installed at the office here at Crown Builders in Charlotte, NC.  The landscaper told me to water each day for 15 minutes the first 10 days.  From 10-21 days after install water every other day.  After 3 weeks and beyond cut the lawn as needed.  It should be fairly well rooted and can take normal wear and tear. Give it 1" of water each week.  Apply balanced turf fertilizer 6 weeks after install.

Yes, we agree with other answers.  Common household condensation, or "sweating" on windows is caused by excess humidity or water vapor in a home. When this water vapor in the air comes in contact with a cold surface such as a mirror or glass window, it turns to water droplets that is called condensation. All homes have occasional condensation, such as a little fogging on the windows, and is no cause for concern.

The best way to get a confirmed price is to look up window installation companies on your local BBB web site.  

Energy efficent windows are a good investment.