question about noises

Yes thats normal. Your new Prius will make alot of strange noises and takes a while to get used to. That specific noise your hearing is the coolant transfer to the thermos. Right after you shut the car off it pumps hot water into a thermal bottle behind drivers side front headlight to store it and keep it very hot. Upon re-start later pumps that hopefully still hot water back into the motor so the motor heats up faster providing less emisions.
The other little sound people complain about at first is if you pump the brakes you'll hear a little motor sound from up front too. Try it. Pump the brakes 3 or 4 times in a quiet area with the car on and motor off. Thats a little vacuum pump that creats vacuum for the brake system. Normal cars get vacuum from there engine but a normal car's engine always runs. Ours does not thank god. So they needed a constant source for vacuum.
Good Luck!

 

If the OP lives in Cyprus, then her Prius will not have an engine coolant heat recovery system since that is a feature of NA Prius only.

If sounds are heard when the car is off, this might be the brake pressure accumulator pump running briefly. It also might be the fuel tank being checked for pressure leaks, five hours after the car is off.

 

Brake accumulator pump. There will be one on any car with a dual-circuit braking system. Pretty much anything advertised with Electronic Brakeforce Distribution.

The Prius brakes aren't actually that alien at all. It's identical in every respect to any other dual-circuit system, barring one: that the Skid Control ECU asks the Hybrid Vehicle ECU how much regen braking force it can provide, and adjusts the friction braking accordingly (for the most part, not doing any!)

You should also hear the pump run after you've used the brakes a few times.

 

Sounds like the brake pump to me, I hear it and I don't have a coolant thermos.