Firewall,
Being brand new and thinking of using Alliant powders, I would strongly suggest you start with Unique. It can be used for any practical bullet weight in 9mm, and works very well when used in reduced charges. Most importantly for a beginner is its high bulk to weight ratio will cause a spill over with anything but the lightest charge weight should you double charge. Once you get some experience under your belt and learn the ropes, Unique works extremely well in medium and full velocity 9mm loads with cast and jacketed bullets alike. Its nature is far more forgiving than say Clays or Titegroup, and the accuracy I get, especially with cast bullets has always been absolutely top notch.
Cons? In lower intensity loadings there will be unburned flakes/soft sooty fouling, and because of its shape/density it won't always meter as easily as say ball propellants. For me the key is to perfect your procedure, be it from a scoop, hand operated powder measure, or measure on a press. Jerky hard stops cause problems, and if I work my 550B with no hard stops and a smooth action my drops are very consistent with Unique. I have read of "bridging" problems (when the powder will stick/clog in a powder measures drop tube), but have yet to experience it. If this does happen, this can be very dangerous as one case may be undercharged, and the next get what remains plus a full charge. Regardless of powder, you should always be on the lookout for it.
A few other comments I hope you will find helpful:
Once you get OAL figured out, make sure to NOT taper crimp the case too much. Basically you just want the belling removed, or perhaps a bit more. Make sure to seat your primers fully, with the flat portion of the primer below flush with the case. Don't go too low on charge weights where a squib could happen, and a bullet could remain in the barrel. I would not use much less than 4.2 grains of Unique, and even then it is possible that the action of the pistol will not function. Trying to say what fps will or will not cause leading is not going to happen, as far too many variables come into play. FWIW, at times I will make up a cheap M882 clone where I drive 127 grain cast bullets in excess of 1200 fps, and leading is not an issue, but sizing/lube/alloy is to negate it.
Good luck, and enjoy your new hobby.