Hi, I am a total novice here, I hope I've chosen the correct category. I 
have 3 questions, but I guess all of them are easily answerable for 
people advanced in this issues.
I have a Raspberry Pi with constant output of 5 V and controllable 
outputs of 3.3 V. I want to install a fan with DC 5 V and 0.10 A.
I would like to
1) limit inrush current
2) enable switching the fan on and off using a controllable 3.3 V GPIO
3) prevent unwanted voltages when the fan is switched off

I wondered what the best options are to achieve this.
- ad 1, I thought maybe a current regulation diode will do. As far as I 
know, I could use an NTC or a resistor + relais, but, depending on how 
I'll program the 3.3 V GPIO it might switch on and off often. I think 
the NTC won't limit the current when switching off and on shortly after. 
An it is not good for a relais to switch so often; also, I introduce 
another coil that can induce voltages. Is this correct?
- ad 2, I could choose from NPN, MOSFET, or other transistor typed. 
Which type (or model, if you happen to know) would be suited to use 3.3 
V DC to switch on the 5 V DC current? I assume I'll need a resistor at 
the base?
- ad 3) how can I prevent the motor from destroying the transistor when 
it is switched off? Will a simple diode parallel to the fan motor do?