There are threads on this, I know, I have read them, probably in the road forum or Bicycle Mechanics.
My personal opinions follow... Use what you want, ignore the rest.
The issues:
1) Brake levers need to change. If your bike has V brakes, you will either need to get the one or two available road brake levers that work with V brakes, or get Travel Agents... You can also switch to traditional cantilever brakes and use standard road levers without a travel agent.
2) Shifting. Depending on your current shifting you will need to find a replacement. Probably stem shifters or bar end shifters (integrated shifters would be too expensive for temporary use in my view) If you have rapid fire or other, you could try to improvise, but it may not be convenient.
3) The seat on your mtb may not be comfortable with the change in body position, so you may want a different saddle for comfort.
There are also other differences between road bikes and mountain bikes that could impact handling, but as long as you don't expect your mountain bike to ride like a true road bike, you are probably fine.
For pedals, I like my Crank Brothers Candy C pedals. Along with my "trekking" shoes from Lake, which are basically mountain shoes with less aggressive soles. The recessed design of the cleat with this shoe allows for comfortable walking while off the bike. Although I don't wear them inside because at my weight there is a little rubbing of the cleat on the ground at times, and I don't like the possibility of ruining floors.