I would recommend ESP FLASH DOWNLOAD TOOL V2.4...
You can download a single file or multiple files , select check box and set address , browse for file's
Personally I don't think much of the AT+ type Firmware, but each to their own ...
I found the later nodeMCU sdk 140 and 150 to work ok for me, thus far, there are a lot of example pgm's available ,, It will take time to code well acting programs...
I've just started using Arduino , It hasn't been too bad, if you've done any basic + c coding.....
There is also Basic Firmware available, and good help avail MMISCOOL
Both Basic and NodeMCU are interperters...
As for the AT+ firmware it appears to me that you have to run a script through the serial port
to do anything usefull...meaning another device to send the serial, just to run you code, unless
theer is a way to emulate serial port, run code out of flash...