you could get a fish tape
For what they cost I would say this is a must for anyone running wires in hidden places. Here in the UK you can get a set of very cheap fibre glass rods that screw together for longer runs. They are really nice as you can flip the whole length over objects pretty easy once you get the knack.
Leave string with the wires in case you ever need to pull anything else.
If you can use cable as a draw string rather than string. It will last longer, not burn the other cables when you are pulling new stuff in and tends to be easier to pull as it doesn't get snagged on cables so easily. A solid core (not stranded) telephone cable is ideal for that job.
I would say trying to line up holes and partitions in walls between floors is asking a bit much, prepare to have to patch your drywall, and if you don't have to it'll be a little bonus

Running cables in homes is a true pain in the ass. I would avoid it unless you really can't find another solution. I did it day in day out for 10 years, it is always more of a difficult job than it looks!
Cheers
Cris.