Gas lasts FOREVER in hobby-only usage. You won't need a huge bottle unless you want to ignore it forever which is convenient. Mine's about the size of my leg I guess....3 ft tall? I don't know the names of the sizes. I think i went 6 or 7 years of occasional usage and a near-full structural rebuild of my Fibird before it finally ran out. Most important IMO to pick a supplier that's convenient, and tha allows direct bottle exchanges. Recert fee will kill you in 10 years if you actually purchase a bottle and it eventually expires. $125 just have have it certified again I think?
Gas never expires so no harm in going too big. But don't waste money on a huge spool of wire if you don't plan to use it up within a year or so. Depending on wher eyou store it I've had entire spools go bad from just taking up humidity in the air over the years. For that reason I favor the small 2 lb spools since it keeps me from tossing them in the trash to avoid contaminated welds if they haze over with a dusting of rust.
