1. If you get low-maintenance plants you won't have to do much of anything except put them in the tank. Java moss/ferns (tropica fern at stores) are good, anubias, hornwort (sheds little pines that can be annoying), crypts, wysteria. How many plants you get is completely up to you. Here's a good website for ordering live plants: http://www.shop.plantedaquariumscent...-Plants_c6.htm
A lot of the time you can't find good plants at stores, or they try to sell plants that aren't really aquatic. So be careful if you go to Petsmart or anything like that.
2. I wouldn't turn the light off all the time if you get live plants. If you get low-light plants, which are generally the least maintenance, you can have your light on for 8-10 hours a day.
3. You do not need to cycle the tank for plants if you get "easy" plants to grow, however, if you have a filter in your tank it would not be difficult (especially with the addition of plants) to establish a cycled tank.
You can always up your water changes to help prevent an algae problem.