Will try to go one at a time here:
1. Sounds like you have the oven at 7200 and not the 12000, correct?
2. The microwave, what is the wattage? It will not pull 15 amps, do not do the math for the wattage.
Most are 1000-1500 max
3.Air Handler will not use 3600 watts. That is a huge motor at 30 amps if 120 volts.
It has a nameplate rating and will list the motors amperage or wattage on the label.
Usually 10 amps max or so for air handling.
4. On the AC, again they have nameplates that should always be used for calculations.
It will list the entire condensing unit as a whole for FLA and may list the compressor and the fan separately. 2 motors on a condenser.
5. The big issue on the sheet, look at cell P48
You will see that it adds up cells P21,P34,P36,P37,P38,P39,P40, P41 and P45
But look at those and you will see that 38, 39, 40 and 41 are heating AND AC.
You only use the greater of the 2 in calculations because you cannot run heat and air at the same time.
To cure the problem, you might use some blank cells as calculations where you add up the AC , then another where you add up the heat, then use one cell to hold the greater value and add it to the total
Its called a Logical IF
You would Highlight a cell then use the Logical formula and enter the below:
Value if True P38
Value if False P41
Now your total will not contain both AC and Heat but the greater of the 2.
Remember also, the AC uses the blower on the furnace too, just no heat strips.
But the blower is minimal in wattage.