I am assuming you meant 1.4" pot, if this is right then yes you do need to repot it. As far as how big of pot...Well the bigger the pot the more it will spread, but I'd go with a medium sized pot, and I am not sure about the leaves getting very big
growing indoors, Once it gets to the desired height, you pinch or prune the top off, and it will make it bush out more. I would recomend a good potting soil and no it does not need to be sterilzed, there are other mixes that others might suggest as far as soil that would work well.