2. Yes, the E2 9mm (229-1) mag is dimensionally the same size as a .40 mag so the new mags will fit in an older. 40/.357 gun but not an older 9mm gun if that makes sense.
3. Yes, although the mags are different dimensionally older 228/229 mags work in the e2 (at least in my experience with my e2 9mm).