I can't tell from your photos if you've wired it together properly, but I've built the circuit on my breadboard and it does work. You do understand that it acts as a current sink, right? You won't get much "signal" from the Pin 7 output, as the circuit pulls Pin 7 low for about half the time and leaves it floating for the rest of the period. So to see if your circuit is working you can connect one end of a 1k ohm resistor to the positive supply, the anode of an LED to the other end of the resistor, and the cathode of the LED to Pin 7, then scope the Pin 7 and you should see the signal. The LED will be flashing so fast you probably will just see it as continually on, but if you make the capacitor larger (for testing purposes) like 10 or 100 uF you should be able to see the LED flash.
To answer your specific questions:
Yes, the 555 version you bought should work.
No, there is nothing wrong with the specific trimpot you've selected. It should work fine.
Yes, the Pin3 output should go to the wiper of the pot, which is _usually_ the center pin.