I searched but couldn't find any answers.
Question 1: Can I power the pin I marked 1. with 5V or is it only for 5V output?
Question 2: the VCC pin is marked 5V in many shields but in mine it is marked 3V3.
Can I power it with 5V?
Thank you
Question 1: Yes 
Question 2: Which VCC pin is marked 3V3 ?
The 5V pin on the Arduino Nano is a output or can be a power input (depending on who you ask). The board in the photo makes 5V from the power barrel jack. In that case it is a 5V output. You probably can use it also to power that board+Nano (depending on who you ask).
Is your VCC pin on the Nano marked as 3V3 ? Or do you have another board then in the photo. Can you measure that VCC pin when applying power to the power barrel jack ?
In the photo, the VCC at the bottom should be 5V. If you have a Nano that runs at 3.3V and 8MHz, then it also runs at 5V.
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Give us please good photo of both sides of your board.
I can not find any "Nano Pro Shield" that has VCC and 3V3 for the same thing.
So the power barrel jack goes to the VIN pin of the Arduino Nano.
The voltage regulator of the Arduino Nano is used to make 5V (VCC).
And the 5V from the Nano board is used to make 3.3V. The 3.3V is only available at the block with three pins (right-middle).
No, it most certainly is not! 
The adjacent pin marked "NC" would be the 3.3 V pin if connected - and in many such breakouts or "shields" it would be connected to the 3.3 V output pin on the Nano itself.
This particular "shield" necessarily conforms to the UNO pinout (in order that it can be used to mount other UNO shields) so the 3.3 V pin - if present - matches that.
Errr, no! 
The "barrel jack" on this "expansion board" and the additional regulator is really no more useful that that on the UNO or Nano itself and should be ignored for any serious project.
On the Nano, the "5V" or "VCC" pin (definitely not to be confused with the essentially useless "VIN") is the preferred pin for supplying power - it is the actual 5 V supply to the ATmega328 and USB interface (and the subsidiary 3.3 V regulator). Unlike the UNO, there is no requirement to disconnect this pin in order to connect to a PC by the USB port as there is a diode between however this also reduces the supply voltage if you power it from the USB jack.
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Well, I think it is. I took a look at the schematic that @Wawa found.
The 3.3V from the Nano is generated by the usb-serial chip and is not stable and weak. I think that is the reason they added a normal VIN->3.3V voltage regulator.
Well you are correct. Almost!
The board cited actually has the AMS1117-33 regulator fed from the 5 V - not "Vin" which some posters have suggested would be better - and connected in parallel with whatever is on the Nano module. But this is not connected to the 3.3 V pin on the UNO pinout which is labelled "NC" on both sides - as it is on most versions of this board. What has confused the OP, ClaudioGasp, is that the "VCC" pin which is indeed connected to the 5 V line by that track snaking around the edge of the PCB, is misleadingly labelled "3V3" underneath.
Some other boards do not have either the regulator or the UNO pinout. Where they do, it seems the UNO "3V3" pin generally is not connected.
OK, well I have had enough of the research at this point. My original intention was to get out a couple of such shields.from my stock and set them up to prove other problems on the forum so if I discover anything else in the process I may have more to say. 
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There is the wrong label, I could not find such a picture. It is 5V.
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