So far as tapes and charts go, if you even think such things might help, try them if you feel like it.  So long as it doesn't hurt the instrument, and you can always take them off later, they aren't anything to worry about one way or the other, in my opinion.  Far too many people worry about such things.  I think that once one starts to hit the notes reasonably well, music itself teaches you because you want to make the song sound right.  

Stages of learning?  Well, it is a progression, and one can decide this is such and such a stage and that is such and such a stage.  Maybe it helps some people to think of learning as having mileposts like that, I don't know.  I can see where it might have some use for a classroom or a teacher trying to get a student to specific goals, but I don't feel it is actually necessary.  The main good thing I can see to it is that it gives some opportunities to feel a degree of accomplishment and to encourage yourself with a bit of a treat or celebration.  That can be good for morale, but one could just as easily reward themselves for every 20 hrs or practice or something.  There certainly will have been some progress in that amount of time.

Professional musicians I have known tended to practice both technique and expertise quite religiously, though.  The best of them also kept up their study of music theory, even if it was mostly to keep their memory refreshed on what they already knew.  Sure, study pieces for performance or recordings or whatever.  But it is not like there comes a time when you leave the basics.  The basics are basic because they are the foundation everything else rests on, and the more solid they get, the better everything else goes.  I don't believe in a time when we get to leave the basics behind.  We just add more advanced things to them and build on them.  

A guitar instructor I had some years ago was a professional session and recording guitarist, and had been for much of his life.  He considered things like scales and finger exercises to be part of "paying your dues".  He used to say that if you wanted to be good, you never stop paying your dues.  He said that being professional was when you figure out at some point that you have paid enough dues that you can also collect on them.  But that you never stop paying your dues or you'll lose your edge.

If we walked in when he was just by himself, often he would be doing the very same sorts of finger exercises and scales we learned in the first couple weeks of class.  But he might be doing them astoundingly fast and/or incredibly clean compared to us.  Sometimes not fast, though, but practising them with a certain feel.  He claimed that the scales and exercises he showed us in class was part of the very same stuff he used himself every day and that he sincerely hoped it was good enough to be of use to us "right through to the bitter end".  It was just basic stuff.