go to wilco's and get any old soil with nute pellets in if you dont wanna buy nute's.
also yeh I allways put a layer of chunky pebbles/stones at the bottem to aid drainage as i dont usually use perlite.
as for the repotting issue somone mentiond there is no problem. with autos it is best to plant it straight into it's final pot so no repotting is needed. the bigger the better in pot size.
personally I would go for a basic soil and get some proper nutrients, but thats just me.