Well, lat pull down is pretty much the same thing, but with less muscle recruitment. If you can lat pull down your weight, you can do pull-ups
Usually people start with lat pull down until they have the strength to do pull-ups, then move onto weighted pull-ups or fancy ones.
No idea if creatine helps or does anything at all. I've never noticed any change or difference after more than 2 years training. I can only go by other's comments or the very rare occasions I measure something. Creatine is quite strongly recommended though, supposed to increase water retention (which makes you look bigger) and improve endurance. It's so cheap though that I see no reason not to take it.
Didn't notice anything when I started taking it, but it's another gradual sneaky build up, so it's hard to tell if any changes are due to that or something else. And now, not taking it, my diet has slipped too, so again it's hard to say if my problems are from low creatine or that