This may or may not be helpful, but… I’m still on OS 10.6.8 and I had absolutely no trouble with the installer or using the importer in PP2012.
Based on what I’ve read, DAZ needs to modify the way they build their bitrock installers to run on 10.8 (something about needing to sign them now that Apple uses Gatekeeper). I’ve heard there are ways to relax the signature requirement to allow any program to install, but I don’t know how to do that or if it’s easy / safe / recommended. I’m not saying that’s the problem… Just that it’s possibly the issue. And DAZ may already be doing this (I just don’t know since I haven’t upgraded my OS and I’m a little hesitant to…). A quick google search on “Gatekeeper” will pull up more information if you want to investigate that further.
For the crashing… If you know the full path to where you want the installer to place the content, you can always pre-type it in textedit (or your program of choice), copy it, try the installer, and paste it in instead of trying to use the folder “finder” option. That used to work on the old installers that wouldn’t let you use the folder or didn’t have a folder to use (in some cases). Have no idea if it will work for this, though.
For both issues, however, I’d contact support (call if you can, but a support ticket would work). They should be able to at least get you the files you need in a format you can use them in if they can’t / won’t troubleshoot the installer issues themselves.