I have Gigaset GS6 Pro with e/OS Murena.
Whatever phone you use, you need an RJ45/C-usb adapter. Then if mobile network switched off and the adapter with twisted pair connected to the phone it just works.
I bought DELL adapter up to 2.5 GBps for £25 but there are cheaper ones on eBay with slower speed provided.
GS6 connects to wi-fi but WPA2 profile needed with e/OS.
Mobile network should work fine.
The memory card slot is under battery cover you need to lift to insert the memory card up to 1TB.
I hope it helps 