The proper way to manually install an IRO is to use the Import button in the Library tab after you have downloaded the IRO from an upload site. Doing this will make a duplicate copy of the mod inside the Library Location you set for Workshop -> Settings and it will be labeled properly inside 7H. Once that happens, you can delete the IRO download to conserve space, but if you ever uninstall the mod from within 7H, then you won't have a copy of the IRO to Import. It will have to be downloaded again.
If you download the IRO and directly place it into the Library Location you set for Workshop -> Settings, then 7H will read the mod in the Library tab the next time you open 7H. It will show up as IDTag_ModName_ModVersion as you described. This is not the preferred way though.
What I need to see is if Update Patches can use the Import button to properly patch and update a mod. This is the main function for having the Catalog, and I do not know if it works manually. If it doesn't, this means that every update will have to have patches made for the Catalog and full versions made for manual downloads. That is a really annoying process to do manually if all I have to offer is a bug fix for a mod that is very small in size, but the mod itself may be very large.
It's madam