thing to think about is the max amperage of your panel, this might need upgrading simply because today's houses has more needs than the ones built 60 years ago (assuming the previous owners didn't have it upgraded as they added on). Did you get a home inspection? If yes, what did the inspector say? If no, I can recommend someone in your area

proofing done and good drainage around the house. I also agree with Inspection Connection as the gutters, downspouts and extension at least 5 feet away from the foundation is crucial to keep as much water away as possible.

If you choose to add the vapor barrier, it would have to go up the walls and be sealed for it to be of any real value in keeping the moisture under.

As for the foundation repair, did the contractor see any cracks in the foundation, walls, doors and/or windows out of square, floors not level?

I would recommend having an independent inspector, engineer come out and evaluate the situation as he/she will be completely unbiased.

minimum amount of opening, adding a screen will restrict the airflow as JL said and the opening could easily get frosted over during winter if you get ice or snow. As for the paint, it is to prevent the vent material from deteriorating due to the UVs, this is why you will find on older homes the lead flashing on top of them.

wet rooms beacuse the drain lines are not imbedded in the slab. Professionally speaking I hate them because I hate to crawl under there :-p. But Allen and Courtier are right about check the HOA if it applies and the terrain.

the window and the curtains. I'm assuming your house is on pier and beam and My guess is your floors aren't insulated. I would add insulation in between the joists, this will also help. The most cost effective way to reduce energy waist is by caulking around windows and adding insulation.