I've made some ESP-PICO-D4 boards, maybe I would write a little design blog. Good idea!

I had this when I had set the crystal frequency incorrectly, and the flash clock speed was too high for the SPI flash chip. I'd suggest trying to use a slow speed flash SPI bus in DIO mode.

I noticed that manually resetting the ESP32 just before launching the debugger helps.
But it is not just Eclipse, same is the case with VisualGDB on Visual Studio.
Probably has something to do with lack of proper support for the reset line driving for ESP32?

I think you should use telnet on Windows and try to make a manual request to see what response you get. Something like GET /anypage.html HTTP/1.1 Host: 192.168.x.x If the response is not proper (such as the length of web page in bytes is smaller than what is specified in the header?), then you may b...

Setting SPI_SIO bit in SPI_USER_REG will enable pin sharing where MISO and MOSI will use the same physical pin for half-duplex communication. So yes, there is hardware support for that. ESP8266 had it too.
When you attach SPI peripheral to a GPIO pad, what do you get?

Nah, the return value will not tell you the status.
You can use the Wi-Fi event callback and detect events there for taking suitable actions. You may want to check the Wi-Fi event handler and its documentation.

If you use an external codec and I2S interface, we may have a good open source solution for you:
https://github.com/IoTBits/ESP32_SGTL5000_driver/

Still working on it, would love to include features if you would suggest some!

I have a test board with just the ESP32-D2WD (nothing else, not even a button) and I get a 5mA in deep sleep mode (using timer wake-up). The chip power supply is 2.6V (not 3.3V as usual). I have been able to get the running current down to 80mA with Wi-Fi on but the deep sleep current is always kind...

Ohh well, I do like the chip. But.... http://iot-bits.com/wp-content/uploads/2017/11/LY68S3200-chip-not-available-to-buy.jpg Would you really want to use that chip in a design at this point? I'd rather wait until it is available to buy from someone (on AliExpress or wherever) other than the manufact...

Wait a second - you need more memory because you are running out of heap? Then this will not help. Heap is in the RAM, and flash is not for that. You could use external RAM like Microchip SRAM (23A512, etc). The RAM chip in WROVER module is not available for sale as far as I can see. And unfortunate...