PORTABLE/GRAVITY FILTER CHOICES

I am looking at two of the water filters trying to compare &  decide which one will remove more chemical pollutants from groundwater. I live in Norfolk, VA, and am told that the main difficulty in using well water here in an emergency is not so much filtration of bacteria & such,which is pretty straightforward, but the chemicals in the water table.
 Of course after I purchase a unit, I am still going to have the filtered water tested at a lab for VOC's and anything else that can be tested before I commit to drinking it, but m intent is to obtain safe filtration of local groundwater for use after a major hurricane. here in Tidewater Virginia, local watersources have already been made undrinkable for an extended period from contamination after a mere category II hurricane (not severe), and no one seems alarmed by this.

 GSS2 Series - Portable gravity filter 10 GPD (40 LPD) two candle system Offers some add-ons or upgrades. One can apparently upgrade the original CN-SS supersterasyl filter to the Imperial Supersterasyl filter  CN-SSI. There are several more possible upgrades listed for this filter system.
 CN-B2 2x4 Fluoride/heavy metal reduction element for gravity drip water filters 2"x4"
CN-A3 2x4 Nitrate reduction element for gravity drip water filters 2"x4"
CN-M1 2x4 MTBE reduction element for gravity drip water filters 2"x4"
CN-A5 2x4 Arsenic reduction element for gravity drip water filters 2"x4"
Do I as the user have to decide which of these2x4 filters I want to use, or can I use all 4 of them in addition to the Imperial Supersterasyl filter upgrade?
May main concern is removing chemical pollutants.

These portable filters are the perfect choice for you to use when there is not a reliable water source or for any periods of emergency. If there's bacterial and chlorine resistant Cysts in the water, it will filter them out. These are all extremely good at removing VOCs from the water. The specialty elements you have listed should only be used if you are using the filter daily for drinking water. You should only use one kind of "add-on" filter with these systems. For example, for city water, typically choose the CN-B2 2x4. If you use a mix of filters, you are essentially only filtering half the water for that specific contaminant.
All three options will provide virtually chemical and microbiological free water. You just have to choose which set-up you prefer and best suites your tastes.