errr if i remember right you should be able to take uptown D trains to get to 9th av. So the fastest way to get there would be to take the N train to 62nd street and transfer to the uptown bound D. You can buy a metrocard at like, every station. From penn you could probably take the uptown A/C/E to times square and then take the downtown N > Uptown D? :C kind of roundabout but it seems like the fastest way there afaik
From atlantic its the same deal, catch the downtown N to 62nd and then the uptown D