1. yes, we are aware with problems opening the archives on MACs, but there is not much we can do about it. I expect your server is not runninc MAC OS, so there you should not have such problem. (anyway, if you need to open the file on mac, repacking it on other PC or using alternative unpacker is a good way around this)
2. the filename does not change with new version. But you can check the version in the xml file in archive; I have check the file on our server, and it includes version 2.3.4
(btw. if you will find version 2.3.4 in the XML, but your Joomla still shows 2.3.2, then it is quite clear, there is something wrong with the files; like that some file(s) were not uninstalled correctly)