Hey pianojoyy.
For both of your concerns, there is info available on the Use your TV as a display with Mac page. Below you'll find a few snippets that may be helpful.
"Connect your Mac to your TV
- Connect one end of the video cable (or an adapter, if necessary) to the computer’s Thunderbolt port
, HDMI port, or DVI port
, then connect the other end of the cable to the TV’s video input port. - If you need to adjust the resolution on your TV, choose Apple menu
> System Preferences, click Displays
, then select Default for display to automatically use the best resolution, or select Scaled to manually select a resolution. - If you want your HDTV to play audio as well as video from your Mac, choose Apple menu > System Preferences, click Sound
, then click Output.
Select your HDTV in the list of devices. If you want to play audio on a different device (such as your computer’s speakers or an AV receiver that’s part of your sound system), select it instead.
Note: If your Mac has a Mini DisplayPort, make sure you use a cable (and adapter, if necessary) that supports both audio and video."
Step 2 in that section seems like it'd really meet your needs as far as the resolution of the TV goes and the size of the mouse arrow and items. For the other issue mentioned, if your Mac has an HDMI or Thunderbolt connector on it, rather than a Mini DisplayPort, sound should send to the TV without issue. If you're not sure, you can find the technical specifications for many Mac computers using the Tech Specs page.
Take care.