No, you dont need to add any live rock. Beneficial bacteria will grow on any surfaces in the system, filter media, substrate, rocks, plants, the aquarium glass. I try to work on 1kg of filter media per 100 litres of water.
With regards to planting, you can either plant before or after cycling. Planting in an empty tank is easier as you arent dealing with plants trying to float to the surface while you are getting them rooted. But, the plants will take up some of the ammonia you are dosing to fuel the cycle, so it might lengthen the process.
This is the first video of a low tech planted tank project, have a look through the series. It got me started on planted tanks.