First the difference you see in the charge station power used to charge and what your car says you've used is caused by charging inefficiencies. Since charging isn't 100% efficient you only get about 85-90% of the energy out of the battery that you put in while charging. The difference is lost as heat. Further 33.5 kWh is the maximum capacity of the battery. You will never be able to use this full capacity because doing so would ruin the battery. Lithium ion batteries degrade quickly when kept fully charged (4.2V per cell) and it is even worse to let the battery sit depleted or nearly depleted. If it were possible to fully deplete the battery it is very likely it would never hold a charge again. By default when the car says it is 100% charged it is only really 90% (about 4.02V/cell if I remember correctly). You will often see this referred to as 90% SOC which means "State Of Charge." So if you see someone refer to a battery % SOC you know they mean what the actual battery charge level is not what the car says. On the other end when the car says the battery is depleted it really has about 5% left. These limits protect the battery from you prematurely killing it. If you plan to keep the car long term avoid running the battery very low as much as possible. Also less important is don't let it sit fully charged all the time. Since the car already limits you to 90% it's not that big of a deal but the battery would be happier long term if it was only at say 80%
Temperature very much so affects battery capacity. Capacity most noticeable starts dropping at about 50F and really takes a hit at freezing and below. IIRC the battery is happiest between 70F and 95F. When it's warm you will have a max usable battery capacity somewhere in the upper 20's kWh, probably about 28-29kWh. Being in the 280's Wh/mi means it's still cool where you live or you are driving at high speeds on the freeway. For reference my winter power consumption can go as high as 350 Wh/mi. I've even flirted with 400 Wh/mi a couple times. Since electric motors are so efficient, fuel economy is the opposite of gasoline cars. You will go much farther in the city than at high speeds on the freeway. Your 33.5 kWh FFE is rated at 115miles of range. This is somewhere about 250 Wh/mi (.250kWh/mi * 115mi = 28.75kWh). That is under ideal conditions. It isn't too hard to beat 250 Wh/mi in the summer. If you've been using heat, that uses several times more energy than the AC. Depending on how much AC you're using, that only takes about 10-15% off your range. If you keep off the expressway you should have a range of about 100 mi with AC. With age and usage your battery capacity will decrease. That is the unfortunate nature of batteries.
Also as a side note for winter conditions: Charging a cold soaked battery is not good for the battery. Trying the DC quick charge a cold battery is even worse! If you can, plug in immediately after driving while your battery is still warm. Once charged, letting the battery cold soak in the winter if you won't be driving the car for a while will not harm the battery. It's just trying to charge a cold soaked battery that is not good. I don't claim to fully understand why charging a cold battery is bad, but I think it has something to do with the cold affecting how the chemical reactions work in the battery. I may have it wrong but I think it results in some of the lithium ions plating out as lithium metal which is not a reversible reaction. Someone more knowledgeable correct me if I have that wrong.
2014 Blue Candy FFE
http://www.fuelly.com/car/ford/focus/2014/triangles/303811 (since this forum doesn't allow BBcode in sigs)