ESP-07 (ESP-8266) introductory questions

[rafa.uy]

Hi,
Ive been working with the ESP-07 module (ESP-8266) and now I need to update the AT commands, but I have been overwhelmed by the amount of concepts and documents. So I would like to ask you help me clarify some concepts. This is what I understand so far:

1-The ESP-8266 is a wifi IC with an embedded microcontroller. The microcontroller flash is too small to hold anything but the bootloader, so the firmware is stored in an external flash IC.

2-The ESP-07 is shipped with a firmware that only processes AT commands, and has no RTOS. Where do I get the binaries to upgrade my module?

3-SDK, this is where it gets tricky. I see there are two SDKs, with or without SDK. Do the binaries that comes with the SDK include the UART AT commands interface to communicate the module with an external microcontroller? Will they run on their own without further programming?

4-I did program the binaries included in the SDKs taking into the account the memory address sepecified on the SDK documentation but it doesnt work, when it boots I get some messages saying that something is not 100% right.

5-A more basic questions, whats the purpose of a SDK in the end? To program my firmware in the module itself?

Thank you very much!
R.