Personally, I would not use a weed and feed product. It does not look like it was applied properly as it is in clumps. Weed and feed products and most fertilizers are best applied with a spreader to get even coverage. That being said, even if you use a drop spreader there could still be clumps near sidewalks and at points where the drop spreader was stopped or turned and the spreader wasn't closed soon enough. Depending on the product and the type of grass you have, there could be some yellowing as a result. Usually it will correct itself if the grass was listed as safe to use the product on and the product was applied properly.
If you read the label on the product it should tell you what to do about watering before and after applying the product. http://www.scotts.com/smg/goprod/turf-b ... od11670004
Most landscapers or their workers usually just do their job and don't really talk to the people living in the house. We had a landscaper for our rental. I hired a landscaper to aerate and topdress the lawn but he called me and told me it wasn't worth doing it because the grass was in such poor conditon because the tenants had turned off the sprinkler system. I had to tell the rental agent to remind the tenants that we charged $100 less than the going rent to pay for the water.
If it is in the maintenance contract for the landscaper to fertilize and do weed control ask the landscaper to let you know a couple of weeks in advance and ask if there is anything special you need to know like changing the watering schedule, if there is any time interval where you want to keep people and pets off the lawn after product is applied. Also discuss what products are being used and look up information on what the products does, precautions, and instructions for use.
Most landscapers around here do not have college degrees and are mostly immigrants and many of the homeowners hire them to do mow the lawn and are not interested in the details, just the results. The landscapers are good at their jobs but usually not so good at public relations. Most homeowners who hire landscapers do so because they want green grass but don't like to do yard work. However, you will get the best out of your yard if you actually talk to the landscaper and ask them what you need to do to keep the yard looking nice.
Unless this is new grass you should not have to water twice a day every day. It would be better to deep water and water less frequently. You still will need to adjust watering for seasonal changes.
Happy gardening in Hawaii. Gardens are where people grow.