Yes the 115 volts you read is just the maximum it will handle.
15000btu is the largest and that's a 115 volt basically the same ,you just need a higher breaker is all
Doesn't sound like a good idea to me.
If it is a 240 volt conditioner it will stop. If it is a 120 volt conditioner it will stop if it is on the leg that has been lost.
Usually in the air handler
yes
12 V
I don't think you can buy a 4000 volt air conditioner.
Perhaps the highest btu available in a portable air conditioner is 14000 BTUs. The air conditioner that has this high btu is the Sunpentown WA-1410H, which is portable.
No, the RPMs of the motor will be wrong and the compressor will be damaged.
If you are about to purchase a window unit, the answer depends on a few factors: 110/115/120 volt units are generally not available in the larger cooling capacity sizes. If you need to cool one average sized bedroom and have a 110 outlet near a window, this should do the trick, and you won't need an electrician to install new wires. If you need to cool an entire house, then you are going to need a 220/240 volt unit or multiple 110 volt units. If you are talking about a central system, then the furnas, or indoor section will most likely be 110 volt and the outdoor unit 220 and you will need to have it professionally installed anyway.
My electrician says no, has to be some rewiring.