Regarding the Hanon exercises:
There is a quite a controversy on this forum over their effectiveness. Although I realize this is unsolicited advice, my two cents on Hanon are that you must realize that much of the purpose of the first 30 exercises concerns finger strength (and of course independence). The general technical issues that the remainder of the book deals with (scales, arpeggi, octaves, thirds, sixths, etc.), I believe, are things that should be part of your daily practice regimen regardless. I hope that this lends credibilty to my opinion that you should proceed with Czerny simultaneously.
ML