Phototransistor Datasheet Confusion
1)  H11AV1 has a current gain of 1 to 3 which is product of hFE and optical attenuation.  This is relatively good for a PT.  Most of the variation is due to LED and hFE tolerances known to often exceed 300%, unlike Photo Diodes which are every stable and repeatable.

2) BVceo  varies with collector current


disregard typical and use the worst case 70V min value.  


I think you understand the polarity but BVceo (70V min) is the reverse of BVeco ( 7V min) which a -ve collector voltage.