Continued dosing won't prepare for a higher initial bio-load unless the dose is increased and the tank is not already surface-area-limited. Even then, the bacteria will start dying back very rapidly, so the effect is very short in duration.
Nitrate kits often work by reducing some of the nitrate to nitrite, and then detecting the nitrite, which is easier, chemically speaking. So small amounts of nitrite will show up as large amounts of nitrate.
Nitrate kits often work by reducing some of the nitrate to nitrite, and then detecting the nitrite, which is easier, chemically speaking. So small amounts of nitrite will show up as large amounts of nitrate.