Hi,
If you are on town supply water there should not be ammonia in your tap water.
The reason for treating the tap water is to remove chlorine and chloramines as well as heavy metals normally found in treated water supplies. Using any of the good tap water conditioners like API etc is a must...
That depends on how many 1 cubic inches fit into 10 gallons. Or if you use microns millions. However if your question was how much room does a fish need to thrive then the answer would be you can't divide it anymore and you don't have enough room as it is.
Small filter, large filter what exactly is the brand and model of the filters. It's really difficult to help you with just those very vague descriptions.
Anyone who has this much of a problem with the dollar cost of some substrate IMO is definitely in the wrong hobby. It is NOT a cheap hobby and never was. If you are having a problem with affordability at this stage I wonder how you will cope if you need to buy meds or other necessities as the...