A visual barrier is all you may need to contain cars to the parking area. If a car is really going to go over, a 18" wall may not stop it. What about continuing the split rail fence around the parking area to define it? This will eliminate the need for the second shorter wall. Dry stack stone walls will take the freeze thaw cycles better than mortared walls and can shift a bit without cracking and becoming unsightly. David Reed a stonemason in Asheville NC has written two books about building stone walls you might like to check out. Last winter I built two dry stacked stone walls, four feet high and thirty feet long in the mountains of North Carolina with native stone from the site. You can see them When Land Hands You Rocks amili

A little of both. I have 11 ft ceilings in a roughly 20x20 great room with 6.5 inchs. The outdoor ceilings with the 8 inch was more like 14 feet ceilings and then there is more background noise outside - and it is nice to help transmit even further since I haven't put deck or patio speakers in yet. I bet 12 feet is roughly the switch over in common practice to 8 inch. There are no absolutes and size is certainly not all that matters. But an 8 inch on 9 foot ceilings would be out of place. It is a bit like recessed cans - 6 inch on 8 foot ceilings is a bit big. I absolutely think you will be fine with 6.5 inch in your great room. You can always go bigger but going smaller would be a mess. You might think that 8 inch speakers are visuallly intrusive.

We spent almost $1K on a phone system with eight wireless slave phones that had an intercom feature. But our systems guy talked us into installing an intercom and we're really glad we did. First, if you call someone, they can simply answer you from across the room without having to walk over and push a button or pick up a phone...very handy. Next, the doorbell rings on each intercom, a real benefit in a house as large (7K SF) and spread out as ours. You can tell the person at the front door to wait until you get there. We've used the monitor feature when infants have visited the house and it works great. Our unit has a built-in radio and CD player but we rarely use that because we have a whole-house audio system and the intercom speakers are low fidelity. But it has a timer that turns on the radio at a particular time and I've used that to remind me about an appointment when I didn't know what room I'd be in. And finally, you can chose from perhaps 20 different door bell tones (e.g., Jingle Bells), not that that's a reason to install an intercom. Perhaps the biggest drawback is that it adds yet more "wall acne", i.e., functional junk on the wall that detracts from the aesthetics of the room.

I looked into control 4 for my house, because I liked the idea of the system and that they purport it's cheaper than some of the other integrated system. For me, it didn't work that way, and my quote was around 30k for the stuff I wanted. Another thing I really didn't like about control4 was that you needed a service call from a reseller technician every time you want to change something about the system. I ended up going with a Legrand Unity system which does very similar stuff, albeit the touchscreen remote stuff isn't as cool, but I still have an LCD screen that integrates cameras, thermostat, intercom, and whole house audio. Speaker wise, I would say 2 speakers is what I would do for that size room, but speakers don't have to be expensive. I bought a variety of types, and settled on Polk 620RT, which look and sound very nice. That being said I bought some cheap Micca speakers off amazon and I think they sound really good; excellent for the price. I'm very happy with my Netgear Nighthawk AC router for $200 (or less on sale). Have them run one of those many cat 6's to two distributed places in the house and you'll be good. If you have to go w/more than 1 router and want it more integrated, I'd suggest Ubiquiti UniFi AC Enterprise WiFi System (on amazon). Cheaper than Luxul and I've heard very good things. -adam