I know I can power the nano through the mini usb, via computer and upload for prototyping, breadboarding etc. BUT can I power it through mini USB, Like from a Switching Power Supply USB Port WallWart (from my old Android Smartphone) with an output of 5V 1A??? I know a computer USB port only supplies 500mAh max. So the wallwart is double the output of PC USB. I know I can power it via VIN pin with batteries and other DC sources. But I am just wondering could I also splice a usb cable and power it via wallwart again, but connect spliced +V wire to 5V pin 27? Also does it matter, if, I power it via (on Board) USB, from wallwart without data connections, just power wires??? This Question would only apply if I can use the wallwart
I think the answer to all your questions is yes.
However, I'm not sure how much current the tracks on the Nano will safely carry from the mini usb to the 5V and GND pins. 1A may be too much. In which case you could as you suggested power the Nano through its 5V input, as well as the rest of your circuit, from a separate power connection from the wallwart.
PS. "mA" is a unit of current but "mAh" is a unit of charge, like the capacity of a cell or battery.
Thank You! I did know the mA/ mAh, thing, but get it mixed up sometimes. Thank you for clarifying that! I thought so but I will always ask an experiencedperson or expert first. Referring to the USb question. And again THANK YOU