Coincidentally I have exact same rooms wired for sound. Family Room is also our main movie area - couldn't dedicate floorspace to a media room. Main channels and center are free standing, prewired for upper front surround (frivolous to most but I dig them - newer surround modes utilize front 'height' channels) and RBH ceiling speakers in the rear. Didn't bother with side channels. The ceilings are adequate and unobtrusive visually but I wouldn't put them in near the same league in terms of sound quality as my other speakers. Powered REL sub is off to the side. Master has in-wall front channels, no center (prewired for a free standing one) and in-ceiling surround. All RBH. Powered sub is off to the side. The system sounds surprisingly good after Audyssey calibration. Good room calibration software makes a tremendous difference and provided proper initial speaker positioning, can help correct all sorts of room-related response anomolies. Basement playroom is pretty similar to Master but I've never actually used it. In-wall speakers will always be a compromise - the wall acts as a huge baffle and causes response issues that are difficult to address through speaker driver/crossover engineering. But we live in the real world where wives matter and budgets rule so that's why I have them. Also be sure you run network to TV locations as well as receiver/processor locations. I store movies on a Network Attached Server and can essentially feed movies/shows to any location in the house. Good luck! Good sound is good for the soul. Bad sound may land you in Bose purgatory.

First....I would recommend a 6.1 system setup. Much better...with a 3rd speaker in the rear. This is not a scientific answer...but the answer I believe is "it depends". It depends on the type of speakers you have and how it radiates. It could work by having it in the corner... I also would think that you could change settings on your receiver to compensate for any issues you might have. Find a great receiver and you should be set. Also...I would think that the placement of the rear speakers are not as critical as the front mains or center channel. That is where you would distinctly hear much differences. Rears are more ambient in most scenes. Hope that helps.

Honestly I think you're way overdoing it. I think you should put two speakers in the kitchen, none in the dining room, and buy decent equipment for your family room. I can't for the life of me imagine why you need four speakers in the dining room, directly adjacent to the family room and right in the air travel path of the sound coming from your front two speakers, which should be the best sounding speakers in the house. The family room, like it or not, is what will be making the sound for the dining room. You will never want to be listening to one thing in the dining room and another in the family room, it will sound awful for everybody. If you did this, one benefit would be that you could get a nice two-zone 7.1 amp and be able to control everything from your phone.

It is very smart to have the pre-wire done as part of the build process. It will save you time and headache later. Origin Acoustic speakers are great. One of the most / only innovative speaker company's around. I don't know which model, but all of their speakers are very good (just make sure they are not the "contractor series". Wired is always better than wireless. There are no true wireless 5.1 speakers systems. They all require power and that means wires will show VS in-ceiling speakers where no wires show and you will barely notice the speakers visually. Not sure you need connection to your "VCR". But you do want wires run to make sure the cable box and the surround sound receiver and amplifiers for the house audio can be in the same location with wires running to the TV location (preferably 1 cat 6, 1 cat 6 shielded, 1 fiber optic wire) With this wiring set up, you can call any local professional (audio, video / home automation / home theater company) who can make sure you are up and running.