My computer and TV are in different rooms with 40'+ distance between them. I have connected them with my HDM1 cable. Do I need a "super range" wireless keyboard/mouse to use with the TV, and what can you recommend?

I have the same setup with plaster walls and closets between the rooms. I extended the dongle to the inside of a closet with a power USB cable. I use Gyration's Air Mouse® GO Plus with Compact Keyboard (GYM1100CKNA). It's designed for presentations and has up to 100-foot range. The keyboard is great, the mouse is frustrating at times. It has a feature that is constantly turning on and off, I guess due to signal drop, that I wish I had the option to lock in the settings app they provide. But it works and probably wouldn't have the issues with standard sheet rock walls.