Its a good idea to reove a little bit of the plating on the back of the pot, use a file or scraper. The solder sticks easier to the bare metal.
I can understand you wanting to change the pickups but do you actually have a problem with the pots, i quite like the 300k ones and the job is easier if you dont have to do that, if they are noisy or scratchy try some pot cleaner first. If you are just changing the pickups it is simply a case of unsoldering the old pickup wires and attaching the new ones, just be aware that there is no standard colour code for pickups wires so follow the instructions that come with them. Once you have the pickups you can always ask again here for what wire goes where.
If you really do need to do a full rewire i would consider getting a pro to do it because, even though its not that difficult when you know how, it can be very frustrating when you are just starting. Really it depends how much you value /need the guitar. Can you afford for it to be out of action for a while if your wiring attempts go wrong. Its always worth practicing on cheaper guitars