Hello,
The IR543 in the kit allows you to control the switch using a universal remote. Your remote needs to be X-10 capable. What remote do you own?

You actually set up the scene at the switch - using the PHC02 Controller - (you can create up to 16 scenes) and then set up a macro on your remote to activate the scene. I’m not sure about other remotes but the MX-700 (that I just received for XMAS and I love it) will allow you to set up a shortcut to a macro from a hard button - in your case play/pause/stop.

Yes, you can locally control the switch.

I buy a lot of my X-10 gear through Bill at http://www.homeautomationnet.com and you can’t go wrong. Bill is very knowledgeable and will steer you in the right direction for what you need.

Good luck,
Carter