So I wired the ESP-12 onto a little board and had my first attempt at programming today. I can clarify the following:
Correction – see where it says “GPIO1 – that should be GPIO2” – some day I’ll keep my originals.
The board needs 3v3, not 5v. The input to the RXD pin should be level-shifted if you’re using a 5v Arduino or similar. As with other boards, the CH_PD pin needs to be permanently tied to VCC – but in addition it seems that GPIO15 needs to be tied to ground – not sure the point of bringing it out! For programming, GPIO0 should be grounded but when not programming you can use if for general IO.
The board programmed up just fine and seems as sensitive as others. Next stop will be to try out using the remaining pins.