AV system networking questions

I'm about to update my 15 year old AV system, and have several questions about the configuration choices I'll need to make. I apologize in advance for the general and rambling nature of this post, but feel free to just comment on the items you may have an opinion on.

I'll be getting a new receiver and Blue Ray player and also an Apple TV. My TV is fairly recent and won't be updated. Right now nothing is connected to the internet, so making this connection will be part of the new setup. Most of my questions are networking related.

I do have an existing good quality wi-fi network using the latest Apple Airport Extreme dual band tower type router. This is located in my office on the next floor from the AV system, but it is only about 30 ft away without any major walls - almost completely line-of-sight. So wi-fi signal at the AV site is good on both bands. My office iMac has a direct ethernet connection to the router. I use the wi-fi over the entire house with no problems on my iPad and iPod Touch.

Most of the receivers and Blue Ray players I'm considering have an ethernet port and support AirPlay directly but do not have built-in wi-fi. So I need to either run a CAT 6 cable down there, use power line ethernet adapters, or perhaps an Airport Express. The house layout makes running a cable a major headache, but not totally impossible. I understand that this would be the most reliable option, but I'm also considering the Airport Express. Would appreciate any comments about this tradeoff.

Whatever I decide, I'll need an ethernet switch so that I can hook up multiple devices to the ethernet. I'm looking at 4 or 5 port switches. Any advice on this? What brands are good?

I see that some HDMI cables now also include some kind of ethernet connection for "supported devices". How does this work? Is it commonly used? Does the Apple TV support this?

Kind of bad timing on my part since there will probably be a new Apple TV in a few months. But I need to complete this before then.

A question about the operation of AirPlay with the Apple TV: Assume I have the Apple TV connected with an ethernet cable directly to my router. Can I access it via Airplay from my mobile devices on both bands? I normally use the 5 GHz band, but have the 2.4 GHz set up as a guest network. Can AirPlay be configured to work on both?

Also feel free to answer any questions I should have asked but didn't.

 

Thanks, folks, for the input. Helpful.

Panch0 - yes, I agree that AirPlay is irrelevant on the BlueRay player. Just listed it as it also has a need for an internet connection for other services than ATV. But some of the receivers have native AirPlay that automatically turns on the audio system when it receives an AirPlay request without need to power up the TV. For me, this seems like a useful feature since probably 95% of what I do with AirPlay will be audio only. Excellent point about using an Airport Extreme rather than Express to pick up the built-in switch function. That would also give me 802.11.ac on both ends which might be of some benefit. Thanks for the suggestion - if I go wireless I may do that.