I have found the intrinsic safety certifications for ATEX and IECEx. Is there a certification pending for the US and Canadian certification (UL/cUL 60079-11 or CSA 22.2). These are outside the scope of the ATEX and IECEx certifications. Acceptance by UL or CSA for intrinsic safety is critical for my applications. We use optocouplers for isolation because we can verify their construction for creepage and clearance spacings. Based on my review of the datasheet I don't know if i could verify this without testing, or without a construction drawing, perhaps CF0001 mentioned in the ATEX report.
Additionally what are the differences in the following pairs
The pin outs on pages 14-16 do not indicate any difference between the pairs of parts.
I will have a check whether we have the plan to get the certifications, and for your second question you will find the answer in Table 21 below.
ADuM1440/ADuM1441/ADuM1442 have the default high output state if input is unpowered and ADuM1445/ADuM1446/ADuM1447 have the default low output state.