That part is the aerial for the microwave. It comes in 2 parts the aerial then the motor.You will need to decide which one is loose.Sounds like the aerial is loose.Take it off and run without if it makes a noise without it on then it is the motor.
It is available part number 494990 motor fan bosch spares.£54.
Remove lid you will see a horn shaped item near front left remove 3 screws then it comes out easy peasy.To replace it is tight fit but can be done. Save money do it yourself.
It will be the cooling fan located near the front left it has a metal blade that has come loose therefore causing the noise.Not repairable will need to replace the fan.
To check the heater remove the right panel and you will see it at the rear disconnect the wires and check for continuity on the element.Personally i would not attach to hot water supply but that is up to you.
it may not be getting enough water in it as the heater works on correct water level. When it fills is a slight thumping noise if so check the pressure chamber on the left handside as this will be blocked clean and run again.
It could be either earth fault on the motor or the heater elementDisconnect each one at time and this will tell you which one has the fault when it doesn't trip supply.
You may find that this oven has a plug on it,Check all your cupboards that are near the oven for this as it is not unusual that some one has caught the socket when putting something in them. The main switch may be just for your hob.
Hot water is used on all washes except under 30 oC so try a wool wash to see if cold water enters if not check water inlet at tap if this is ok probably valve magnet at rear of appliance.
The drain hole at the base of the freezer (behind the cover over the evaporator) is blocked. Defrosting may work but if you can remove the cover you will be able to get at it that way.
Fd numbers are located near the enr number. If fd is 8601 it was made in jan 06. So you can see the first two numbers are the year (8 represents 0) and the second are the month . Youre guarantee is from date of purchase not the age of the appliance. As for parts dead easy just contact bsh...
It is a model number but not reconized by the search engines (reconized on the bshappliance care site),did you take note of the FD number next to the model number?this indicates the age of the appliance.