Positions on a chromatic
I'm not a chromatic player, and I'm just learning music theory on this website. I just watched the Mark Hummel interview, and he and Dave talk about 1st, 2nd, and 3rd position on a chromatic. I'm confused. I think of a chromatic as a piano: it has all the sharps and flats on it without a need to bend. Are 2nd and 3rd position on a chromatic just playing in G and D? Or can you play a song in a different key and a different position? IE, can you play a song in E in first position or second position on a chromatic?
Chromatics come in different keys; C is not the only key of chromatic. You can hear George Smith and William Clarke, for instance, make extensive use of chromatics tuned to different keys, usually in third position but sometimes in first.
The word "position"applied to harmonica simply means the relationship between the key of the harmonica and the key of the music you're playing on it. So playing in C on a C-harp or in Bb on a Bb-harp will be first position, while playing the C-harp in G or playing the Bb-harp in F will be second position and so on.
Whether you need to bend to supply notes or have a slide and a reed for every note has nothing to do with the position concept. Those are simply details that work out in different ways on diatonic and chromatic.
If your only harmonica was a C-chromatic, the idea of positions would be pointless. But players often seek out different keys of chromatic so that they can play it in third position. For instance I remember hearing Bill Clarke absolutely roast a Low F-chromatic, playing third-position blues in G.
To answer your specific last question, To play in E on a chromatic in first position, you'd need an E chromatic. To play in E in second position, you'd need an A chromatic. On a C chromatic E would be 5th position (just like on diatonic).