1) Consider YOU choosing the paint brand and paint grade and let the contractor purchase the paint. The contractor will have a discount at the paint store and this will save you money. You should know how much the paint cost figures into the cost of the job.
2) I like Sherwin Williams paint and I buy the best paint they have. The majority of the cost of painting will be in the labor, not the paint, so buy the best, longest lasting paint. If it lasts a couple more years, it will be well worth the extra money. I used to paint houses and I can tell you they have made a lot of improvements in paint technology. A good quality paint will last a lot longer than the oil and latex paints of 15 years ago. The same is probably true for other paint brands. I think you get what you pay for. You want to avoid contractor grade!!! Don’t let the contractor make extra money on you by using contractor grade paint. Most people won’t ask!!
3) Do the same with the caulk. They have made the same improvements with caulk. Sherwin Williams now has 60 year guaranteed caulk. Not that you will be in your house for that long, but it is an indicator of the highest quality caulk. The caulk is really important because it seals the cracks that let the moisture and air into your house and a good caulk job will help the paint last longer. A good caulk is every bit as important as the paint, or more so.
4) There will be several grades of paint for both interior and exterior paint. The marketing guys bring out a new paint every year or two because everybody wants to buy the latest “thing”. The same is true for paint. The newest “stuff” always has the latest technology and costs a little more than last years “stuff”. I always want the edge of better technology in paint. What ever the improvement is, it usually helps the paint last longer or the color stay true longer. You will probably have at least 4 grades of paint to choose from.
5) I had a window with rotten wood in it. Instead of replacing the window, I had a separate contractor clean out the hole and fill the hole with an epoxy type material, sanded, primed and painted. I did the priming and painting. I did this about a year ago. So far, it looks like new. I will be curious to see how long it lasts. We also had some rotten wood parts on our porch posts. The same contractor replaced the wood parts with plastic replacement parts, which won’t rot in the future. You can’t tell what the difference; it all looks the same. The structural integrity is the same or better. If your contractor is qualified to make this repair, it should be considered.