Marrtyn:
When the bike was new, I had hit the petrol pump nozzle a few times to the central rib, immediately below the gas tank cap, that took off bits of paint into the gas tank. I am not so worried about these small bits. I have heard that the fuel pump has a large net that is big enough not to be clogged easily and catches these bits. I have not taken off the fuel pump to actually see it but the information is from one of our Forum members who has done it.
To remove gas (petrol) from gas tank, you can buy a siphon with a pump that can pull out petrol - no need to use mouth. Other option is to run the bike to burn off as much petrol as you can, so that there is only a little bit left in tank. Then raise the rear wheel high so that petrol collects in the front of the fuel tank. Since the fuel pump is at the rear of the fuel tank and petrol is in the front, you can unscrew the fuel pump without petrol coming out of tank.