Does the 20719 have an onchip 32kHz LPO?
[CY] Yes, it has an internal LPO however we always advise using an external LPO as it greatly improves power and accuracy.
Can this be used for running the BT in Low Power mode, and is it available in all power modes(idle, sleep, deep sleep)?
[CY] LPO operation is handled completely by the low level FW and is used whenever possible to save power.
Do you need an external 32/32.768kHz crystal?
[CY] See above. Yes, we advise using an external LPO. We would need to consult L3 HW/FW teams if you try to move forward with a design where it is not included. It is always risky to stray from the reference designs.
If not, why does our dev board have it? Does it affect/improve performance?
[CY] See above.
Is there a tool outside of WICED for programming the Flash/RAM (I assume over UART) that works in Windows?
[CY] chipload.exe can be used if a CLI is needed (used by the SDK in the download process). Alternatively, ClientControl (also found in the SDK) can be used if a GUI is required.