well Dave, I see that the contractor posted his findings so I wouldn't worry too much about upsetting or offending anyone. it isn't unusual for there to be conflicting opinions, but the fact is that you and he are the only ones who have seen the ductwork. his discription of your return air setup is suspect. I see he is advising you to wait out the summer to do any duct/return modifications. if you can, do. it is awfully hot to be modifying ductwork this time of year. a rushed job isn't a good job. better someone take the time to properly install and seal ducts. it kinda bothered me that no mention of duct or return sealing was mentioned. of course the discussion is pretty technical. but I find that leaky ducts/returns are often overlooked. when you talk about the kids rooms and the 3-4 temp difference, you mention west facing windows. how many & what approx size are in each room? what type of windows do you have? single pane, double pane? metal frames, vinyl frames? clear glass or low-e glass? if the temp difference is due to the west windows..and it would be here in my area, then there are a couple of things you could try. block the afternoon sun from the exterior for a day or two and see if this evens out the 3-4 degree temp difference. wouldn't have to look great, or be permanent, just stop the solar gain. if you can keep the heat from entering the house, then the a/c doesn't have the added load to temper. exterior shading is the best route. rather than interior shades & curtains. beat the heat before it gets inside. if this works then invest in solar screens. yes they are darker than normal screens, but they will minimize heat gain. if windows are double paned..you can't install window tints as it will increase heat between panes and blow the seal. awnings and bahama shutters are other options but to me..at this point solar screens would be more cost effective. right now you have more time than solutions, so give it a try. don't worry about riling those guys up..they live for that stuff. Shophound & the guys have a good handle on things, so let them talk themselves around. I have to admire your restraint & patience. you are aware that 1" pleated filters are very restrictive? for now I'd change to a less restrictive filter. at least then more air will return to the unit. hang in there. best of luck.

I'd start out with visual inspection in attic. if insulation is entering in xxx rooms, first check ducts & supply boxes in attic at these rooms. look for ducts that have been torn, or have come disconnected. it could be that when the work was done on the duct system that insulation fell into the supply boxes, or ducts as they were installed/reworked. I find that cellulose is the most invasive insulation, the fine particles find every entry point in to the house have hvac company come back out. go into the attic with them. just let them step first & watch your balance. a visual inspection will tell you a lot. what type ducts do you have? flex or hard pipe? can you post any pics? best of luck

Why would you want to do that? You should have a properly sized hood over your range. You can do a custom wood with an all-in-one insert, a pre-made all-in-one like those posted above or a custom or pre-made with a remote blower. More: https://bamasotan.us/range-exhaust-hood-faq/

It is hard to tell from this one drawing how the supplies and returns are connected. Is the main supply located in the attic? Are the supply vents 4 feet X 1 inch? If so then why so many and so narrow? I am not used to seeing these type of vents. Is this typical for new builds in Florida? Are the fours vents at the top supplies or returns? The supplies should be near the big south facing window, and supplies on the east and west wall, with the returns on the north wall. The 90 degree turn in the main duct needs to be rounded. If it is built as drawn there will be increased air turbulence and noise. If the duct work is in the attic then is should have R-8 insulation.