Hi Norhund , it will probably take about 4 hours to fully charge when you use the 7kwh charger as you will be delivering approx 3.7 kwh into the car , so its not too bad.
Now the refusing to to drive in electric mode a lot of the times is an interesting one. I think its been covered in the plug in forum , but basically in hybrid mode it should work in EV only until 24 mph ( approx 38 km ) then the ICE ( petrol engine) will start.
You can if you wish when you get in the car press the EV button ( by the gear selector) and this forces it to only use electric even if you go above 24 mph ( 38km), so you could use it in this mode until the battery runs out, then the ICE will kick in. This is the option i use and then i can manually select hybrid mode when i want to , this is normally when my trip is more than the range of the electric and I'm driving 60-70 mph ( 96-112 km/h) on the motorway.
I know this seems like a faff but you get used to it and make the journey more economical if you return home with no electric left.
There are some circumstances where you cannot switch to EV mode , and the main one is if you have the heater on , and heating more than the outside temperature, as it uses the heat from the water going around the engine , exactly the same as any ICE car to do it.. So with the heater on , the ICE kicks in ( but you can have the heated seats on , and as this uses the 12v battery , this does not start the ICE).
In theory once the engine is hot and delivering the heat , you can manually switch back to EV mode and it will keep blowing hot air until it gets below the required temperature , then the ICE kicks in again to raise the temperature., and you could go around this loop on a long journey lol.
Look at "freezing of fuelling" and to "phev or not to phev" in the hybrid section of the forum as there may be more info there that might answer more question you may have