No to both parts.Now did you just make that all up or is it a collective of googling.
Precisely. Heating is designed on the basis of raising the temperature from A to B, say by C degrees. It doesn't matter what the value is of A, the heating system will only raise the temperature by C degrees.When heating is being designed one of the factors that is not included is when was the heating last on.
Maintaining the temperature at B is a completely different matter. It may take 15kW to heat a cold house from -2C to 21C, but it doesn't take 15kW to maintain the temperature at 21C, even if the outside temperature drops below -2C.