Legato/Staccato is not about note duration, but the kind of attack and the shape of the phrase. You can play staccato with pedal (and several composers ask for this!), once your attack is brusque, aggressive, sharp. You don't need to do legato sustaining the notes with your fingers, but you do need to play it smooth and round. Sustaining the notes with your fingers is the easiest way to achieve this, even in octaves, but it is not always possible. Also you will only hear these subtle differences if you play a good grand piano, with very rich tone.
My perception is that piano technique has some very few simple principles that once you master them all the rest is development of musicianship. Listening to a lot of great pianists from first half of 20th century is the best way to improve your technique.