Essentially all the non-loyalty side missions from all the characters will consist of nothing but completing the activities and targets already marked on the map. Kinzie's will always entirely consist of Store Hacking, whereas the other characters' side missions will be more varied. Ultimately, completing every side mission will require you to complete basically everything on the map, though you will only need to get bronze on the activities.
As to your second question, no, you cannot get the sidequest's rewards just for doing the activities/targets on your own without the mission. You can however do the activities/targets long before taking on the mission, and complete the mission in basically no time at all once you take it. At most, you'll need to head into the simulation, walk around a bit while people talk, then return to the ship to get the reward. You can even get partial credit; if a side mission has five activities in it, and you've done three before taking on the quest, then three objectives will already be complete, and you'll only need to do the other two.