Question: Connecting USB and COM1 to Raspberry Pi

[maxpolzin]

1. Is it possible to connect a MosaicHAT to the GPIO pins of a Raspberry Pi and to the USB ports at the same time without risking damaging of the chip? See the attached picture for more details on the wiring.

2. Is it save to have the MosaicHAT permanently connected to a Raspberry Pi's GPIO pins even through restarts without damaging the chip or board even though the the rpi might send random signals to the chip. If yes, how does it link to this section of the hardware reference: "Do not drive a non-zero voltage into input pins (pins type “I” in the tables in chapter 3)
   when the module is in standby, i.e. when the VDD_3V3 supply is turned off."

Background:
I cannot get a point-to-point pppd connection working from a linux computer to a MosaicHAT via its COM1 port (which should be possible through a rpi's gpio pins), but I nevertheless need to have access to the MosaicHAT's webinterface which I do not have over serial.

[jiargei]

It is no problem to connect PINs and USB at the same time!