I was never a fan of the mind reading, telepathic animals.
I think I would introduxe different strains of the virus produxe the different reactions. One variant makes the person revert into a 3 year old, and another makes the berserk rager with the impossibly high adrenaline count. R417A, B,.
The massive fires that consume suburbia or small towns when there is no water pressure and no fire department has driven people into the cities and remaining hard structures.
I would try to encourage GMs to write scenarios where the plays have to create the means to support themselves. Solar power still requires special components not found in an ordinary home or on the shelf at Lowes/ Home Depot. Charge controllers, massive batteries, sine wave controllers. Even the fuse panel in a regular home isn't compatible. The have to find an electrician (or be one) to set it up. Do it wrong and you destroy components, start a house fire, or electrocute yourself. Make it missions to find seeds, find someone that has gardened, a carpenter to build a greenhouse, seek fertilizers or lime/soda. Whether it is a electrical car or fuel one those need maintenance and repairs seek out a mechanic to join your group. Sift through the wreckage of a smash auto parts store for the right brake pads without the inventory (it was digital). Make them sweat over ammunition, few owners have more than one box of ammunition for a firearm, even hunters. This means 20 or 50 for pistols, 20 for a rifle, and 25 for a shotgun.
Maybe a system of starting points for the player to begin with. 1000 points. Items have a value of 1-1000 points. The skills you choose for your character earn you more after a initial cost. Base skill 0, increments above the base skill get you buying points. Lets say 10% Handgun gives you the knowledge to handle a firearm safely. You're not a good shot, but you won't shoot yourself out of ignorance. You would be able to carry safely, load and unload the internal or detachable magazine, and do a basic cleaning. 25% skill and you have a 1 in 4 xhanxe of hitting a target though you are not skilled enough for a shot to wound. At 25% you wouldn't be a to say "I am for a leg". At 50% you would be able to hunt with your firearm, make xalled shoots, and any points used to buy skill above 50% gets you buy in points at a rate of 5% equals 1.
I am a fan of the 100% system. I find it is convenient to explain ability and easy to build modifiers for failure or success.