I think the correct term is "polls" or "poll-pieces". They are the individual metal things in the pickup, one for each string. In some cases, the height of these are adjustable. It's more common for humbuckers to have adjustable polls/posts but some single coil pickup sets are adjustable too. I'm not sure if yours are adjustable but if they are, that could solve the problem with the G-string.. if not, then yeh you need to start to think about what kind of pickups you want.. Active, Passive, or some of the new Hybrid ones that I have seen around. Most people go with passive pickups on a strat because it gives the the standard strat sound.. I personally prefer active pickups.. it's a personal preference. May be research into the pickups your favourite artists use and go from there.