Don't cover the boiling wort, although you could help keeping the wort hotter by putting the lid on part ways. You also do want to boil off a certain amount of water from your wort. It drives off DMS (the cooked cabbage smell) while increasing wort gravity.Also, I would think a reflectix "jacket" for EVERYONE'S pot is probably a great idea -- reduced the time it took to heat my water to boiling significantly (I'd say almost in half).
Now covering the mash is a good idea. You can use aluminum foil for that, although it's not the best solution, LoDO wise.
Yeah, don't use silver flakes shedding Reflectix.