I'm in a similar position to you, although perhaps a bit further down the research curve. I've been looking into LinuxMCE since before it existed (I started considering it when it was only available as "Pluto").
It's confusing, but not that confusing.
Are you going to have a central server location available? ...or is one of the machines that you identify as a joint core and media director (a "hybrid")?
Generally a core needs to be a nice server type of machine. It doesn't require a fast graphics processor. Any media directors (or hybrids, in the case of a core) need to have a supported nvidia graphocs card, capable of providing the resolution that you want to display. This is very important. Think nvidia only (unless you want trouble).
Linuxmce will work with NAS. It requires two network interface ports/cards (NIC's), and needs to be in charge of your network (this refers to your core). It's possible to get it working in ways other than this, but you really need to know what you are doing.
The Acer Aspire Revo R3600's make really nice media directors in their basic (cheapest Linux version) guise. You can mount them behind monitors for a very tidy/portable media director - they may work nicely over wireless (which is built in) for streamed audio or photos, but you would likely need a wired connection for streamed media (particularly HD media).
So, you will need a core (or a hybrid core including nvidia graphics card). You may be able to use your existing computers, but you may have to bite the bullet and buy new media directors, in the guise of Acer Aspire Revo R3600's - it's a pain but they are:
1. Cheap to buy.
2. Cheap to run
3. Use little power and generate little heat so can be left on for instant response from media (ie turn on the screen, and you're in LinuxMCE).
You can use a web-orbiter on any device with a supporting browser. There is a suggestion to develop an orbiter fro android. One way or other you should be able to get the control you need from your handset.
I don't know about Panasonic, but Onkyo is a good choice I have just bought a TX-SR706. There are the codes floating around for programming it through the rs232 port. so ultimately I expect to be able to select to watch a movie in a certain room, and Linuxmce will setup my television, audio, and lighting approriately (theoretical at this point, although my LG televisions are also programmable, and I have put in a KNX home automation lighting and power system to be able to integrate with LinuxMCE).
Good luck. I'll do my best to answer anything you want to know. As I say, at this point this is based on my current thinking for how my system will work.
