the $csvfile variable should be the path to the csv file, yes, yo ucan use a path, keeping in mind its not a web path, its a path based on the OS.
Question 2, The directory month was only for illustrative purposes, I find it easier to contain items within months, as I keep at least 1 year retention on all transactions, but thats me.
Question 3:
Yes, exactly, that names the file using the date function, if you have any questions on that one, see the manual page.
$fileto is the PATH and FILENAME you wish to use,not just the path.