No, it will not; nothing to do with your speakers. Its function simply is to transfer data (movies, songs, etc.) from your device to your TV. It will sound the same no matter the source.

No this simply passes a video and audio signal to the TV. The picture and sound quality are specific to the TV.

Yes, using your smart phone, computer or tablet

It will stream audio at the same quality but the connection from the Ultra is HDMI only, the Chromecast Audio had dedicated audio outputs rather than video.

Yes you can. What you need to get started A Chromecast device Latest version of the Google Home app Google Home app A Google account. A display device with an HDMI input, for example, a high-definition television (HDTV) Access to an available power outlet and a secure wireless network. Meet the minimum Operating System (OS) requirements to run the Google Home app Google Home app An internet connection. Access to a secure wireless network (make sure you have the wireless network password handy) For Chromecast (1st generation), connection to a Wi-Fi 802.11 b/g/n 2.4G network. For Chromecast, connection to a Wi-Fi 802.11 b/g/n/ac 2.4/5G network. For Chromecast Ultra, connection to a Wi-Fi 802.11 b/g/n/ac 5G network. A compatible phone or tablet Availability and performance of certain features, services and applications are device- and network-dependent and may not be available in all areas; subscription(s) may be required, and additional terms, conditions and/or charges may apply. Set up Chromecast or Chromecast Ultra The initial steps are for first-time Google Home app users. If you’re already set up a Chromecast device and are setting up another device, you can skip to step 7. Plug in Chromecast. Install the Google Home app Google Home app by navigating to g.co/home/setup on your Chromecast supported iOS device. Or click to download the Google Home app for iOS. Make sure to connect your mobile device/tablet to the same Wi-Fi network that you intend to use to set up your Chromecast device. Open the Google Home app Google Home app. On the Google Home app's home screen, tap Addand thenSet up deviceand thenSet up new devices. Confirm Google Account: Choose which Google Account you want to link to Chromecast. You can also add a different account if you don’t see the account you want to use listed. Tap Ok Bluetooth: If you already have Bluetooth turned on, you won’t see this screen. You can skip to the next step. Highly recommended: If you don’t have Bluetooth turned on, the Google Home app will ask you to turn on Bluetooth to help improve the setup process. You can swipe up from the bottom of your Home screen and turn on Bluetooth. If you don't want to turn on Bluetooth for setup, Tap No thanks. Tap your iPhone’s Home button and then tap the Settings app and then Wi-Fi. Connect to the Wi-Fi network that matches your Chromecast device. Look for something like ChromecastXXXX.b. Navigate back to the Google Home app. Your device should now be detected. Tap Next. Then skip to step 9. Scanning for Chromecast devices: The Google Home app scans for nearby devices that are plugged in and ready to set up. If you only have one device that needs to be set up, tap Next. If the Google Home app finds a list of devices, tap the device you want to set up and then Next. Found devices: If one device is found, tap Next. If multiple devices are found, choose the device you want to set up and then Next. If you don’t see your device, tap Don’t see your device. Connecting to your new device. The app will now connect your phone to your Chromecast so that you can configure it. Making a connection: We are now establishing a connection with Chromecast. If you see a code on your TV, tap Yes. If you don't see a code on your TV, tap Try again and then Scan for devices. Help improve your device: Automatically share device stats and crash reports with Google to improve everyone’s experience. Tap Yes, I’m in if you would like to help improve your device. Otherwise, tap No Thanks. Here's more about what data is shared when you choose this setting. Region selection: You may need to set your region. Tap the region list and then select your region and then Continue. If you don’t see this screen, move to step 14. Room selection: Choose the room where your device is located. This helps you identify the device when you want to cast to it. Tap Next. You can create a custom room room by tapping Add custom room and thentype in Room name and then Next. Connecting to Wi-Fi: If you’re connecting via Ethernet, skip to step 16. Choose the Wi-Fi network you want to connect to your device. Tap Next. If you selected a Wi-Fi network from the list, you’ll be prompted to enter your Wi-Fi password. Then tap Connect. The Google Home app will remember this network when you set up more devices. If you don’t want the Google Home app to remember this network, uncheck Use this Wi-Fi network to set up future devices. If you selected Other Wi-Fi network, you will need to manually enter the Network Name, Password, and select the Security Mode you use with your network. Ethernet: Follow the steps to set up using Ethernet. Linking your Chromecast: Your Chromecast uses your Google Account to personalize your experience. Tap Continue. Summary screen: Here’s a review of what you set up. You can choose to set up other functionality. Tap Next and then Continue. Learn how to cast: Choose a sample clip to learn how to cast or tap Skip tutorial. Set up is successful. You're all done! Email subscription: Discover tips and new features with email updates for your device and the Google Assistant. Tap Subscribe.

Thank you Ludwig. Now the followup: if the device on which I am running VLC does not support 4k, but the version of VLC and the receiving device do, and the file is a 4k file, will the rendering on the receiving device be 4k, or will it be at the resolution of the sending device that is running VLC?

No it will not.

Yes