Glad to see at least some semblance of interest! 

The feel will be like fallout but a little more up-beat. There won't be any super advanced technology on your average joe such as force fields or death rays but there might be laser guns and metal armour although the armour will probably never be big and bulky like power armour. Also most of the technology is make-shift from older technology like a laser rifle could be made from microwave from before humanity fell.

As for your question on us being frontier folk the answer would be no. The existing 'cities' are still very small even after so many years due to the unforgivingness of the wasteland that humans now find themselves in and most humanity is to scattered to even make an attempt at building a city. The biggest towns population would be somewhere around 800 people so seeing a full blooded human while walking is fairly unlikely. Now onto the cool part about the magic.

Now so far I have two uses for the radiation type magic. The first is a cult of people whom live in a single building way off in the very middle of a wide open plain who are very secretive and most are said to be evil. They all got their power from a single person who had exposure to a unprecedented amount of radiation which allowed them special capabilities that defy some laws of the universe. This person was very powerful and formed the cult from her own followers that sought refuge from the wastes with her. She would give a fraction of her power to certain individuals who in turn gave a fraction of their power to other individual and so on and so forth. That was close to the fall of humanity and now most knowledge about them is a mystery and myth. The second form of the radiation magic I have so far are essentially were-wolf/wolf-man type creatures. This has a bigger affect on average people as the people with this disease are more often than not slaves for rich people and corporations. The disease was originally created when a small dog also survived a unprecedented amount of radiation that lead it to become more intelligent and give the gift/curse of making those who come in contact with its blood people of the wolves. This dog had never been caught and is thought to have died out but legends still say its still around and kicking. Now the disease doesn't work in the standard way of lycanthropy, this happens in stages. In the first week or so the persons canines begin to lengthen and their body hair begins growing out more, in the second week they begin to have more muscle growth and even begin to have a tail stub that is incapable of movement as the brain doesn't have any pathways to get signals to the tail yet. The second stage is the last of the standard slavery stages and is typically used as manual labourers. At the third stage which happens in the fourth week the person begin to radically change into a more bipedal wolf like form growing a snout, functioning tail, claws on hands and feet, incased height and senses and looses the ability to speak properly and use the more human like part of their brain such as facial recognition and such. Along with this third stage werewolves are usually hunted down once they get to this point as under normal circumstances the owner of said person would not want a mindless and ruthless beast running around. Now there is a fourth stage but like many things this is just a legend as no one has seen a werewolf after the third stage but supposedly far off in the irradiated forests to the south there is a pack of these fourth stage werewolves. Fourth stage werewolves have now become more animal than man in appearance as they now resemble a six foot tall wolf human hair but their minds have found a balance between the canine hunting capabilities and the humans intelligence and processing capabilities. It is unknown wether or not they know about their past or if that was wiped out during the third stage. There is a cure for the werewolf process but it is a costly process and could also kill said person. Silver, the highest equivalent of currency on the planet currently can be administered in small doses to absorb the special radiation of the werewolf curse and effectively cure a person of the curse or in smaller doses keep them in the first or second form for slavery purposes. Now alternatively it can be used as an effective weapon against werewolves as a single bullet can force the body of the werewolf to collapse in on the mass of its once human body.

Thats about all I got so far for the radiation magic.