Well I will start with your first post [since my last response]. You have not given me much to go on. You gave me no direct examples of what you could or could not get to work so there is little help I can give. I think I said the following earlier I think you have just started downloading torrents which are zipped. I have never heard of a bug or virus or whatever that magically makes your torrent files appear zipped when they are not.
Most torrent sites have the ability to look at a file list before you download the torrent. Take a look at that list. If the filenames in that list are the same on the site as they are on your computer then you can eliminate the possibility of something weired happening with the files as you are downloading them. I will add that I am about 99.9999% sure that you will find that the file list on your computer will match the list of torrent files on the site where you are downloading the .torrent file. I have seen directly or indirectly a lot of weird problems in torrenting . . . I have never seen anything where the file lists do not match . . . unless the downloading user has purpously renamed them. Simply judging from the questions you are asking . . . I do not get the impression that you even know how to do that . . . so I am pretty confident that the files names you are seeing are the same as the original uploader intended.
If you really want . . . you can PM me a link to the torrent on the torrent site where you are downloading these torrents and as long as I do not need an invite to get on the site in question I can check it out for you . . . but again I think the odds are overwhelmingly leaning towards that there is nothing happening with your torrent client magically changing file names.
Ok moving on to your next post. A .nfo file is a simple text file. It could have information about the torrent itself or information about the group of users who released the torrent or something like that. In some cases there will be information in the .nfo file which describes how to use/un-archive/unpack the files of the torrent but strictly speaking that is not what a .nfo file is for. file_id.diz is a plain text file containing a brief content description of the archive in which it is included. Honestly I have not seen them in a long long time. They were mainly used back in the BBS days (for me anyhow that was over 20 years ago LOL) they are also used in warez (aka "The Scene") for reasons I have never fully understood. If you want more information about it check out http://en.wikipedia.org/wiki/FILE_ID.DIZ
I am just trying to give you some information about what you are seeing and why you are seeing it here. If this and the following paragraph makes your eyes glaze over . . . just ignore it LOL
What you are describing with multiple zip files with sequential names is something I have not seen in many years either. Usually when you are getting a "scene" release there are specific rules as to how the data must be formatted it is typical that they are broken into a different type of archive with sequential names. I can never recall seeing sequential zip files like you are describing in torrenting. The only places I have seen them is when (again about 20 years ago) I used to download a lot of video and or picture content from usenet newsgroups. The whole "the scene" thing is pretty complicated and confusing to a relatively new file sharer. You can go to wiki and read up on warez a.k.a "the scene" but the jist of it is . . . it is a method of file sharing. There are very sepcific rules for "the scene" one of those rules is to included a .nfo file as part of a release (you can think of a release as analogous to a torrent) another one of those rules is that when you are releasing compressed data (meaning zipped data) that you should include a file_id.diz with the release. However, to the best of my knowledge zip files have been frowned upon for about a decade in "the scene" so what you are seeing is a little weird in that respect. In general the scene prefers using an archive system called pararchives. But I guess there could still be a few old fashioned release groups who use zip instead . . . but like I said I have personally not seen that in about 8 - 10 years.
I honestly think that you should check with the torrent site where you are downloading these torrents for more information. Or depending upon the torrent site you may want to just ask in the comments section of the particular torrent a question like "I can not unzip these files on my Mac. Can someone tell me how to unarchive the data from this torrent?".
Not to put too fine of a point on this . . . but you are asking for pretty specific advice about specific torrent data on a forum which is intended for specific advice on a particular torrent client. Those two things are not exactly compatible LOL.
Personally, I do not mind trying to help. But without seeing the exact torrents in question it is very hard to give you specific advice. So as I said if you want to PM me a link to the torrent site in question . . . I can see if I can download it and use the data and let you know what I can find . . . but short of that you are probably going to have to ask for help on the torrent site in question and or ask in the comments section of the torrent in question.