Hi,
Welcome! I think you will be able ot get TV Rename working for you from what you have said, but you may need to adjust they way that you maintian your library a little.
Firstly - as a general hint, I would only try scanning one show until you have the settings about right for you. (right click and 'Quick Scan xxx'). This is just a quick way to scan through and see the impact of some of the (many) settings.
Have you run the 'Bulk Add' feature on your existing library to add the shows in your library to the app?
Taking your message one sentance at a time:
I want TV Rename to scan my 'Search Folder' (where my new TV and movie files go) and rename them using TVDB or similar. I'd be happy for it to move them into my Media Library, but I'd prefer that to be optional if possible and I'd like to preview any changes before I commit to them.
* Yes the general process is to run a scan, review the proposed actions and then 'Do' those actions.
* TVR is built around the idea that it is planning to move files from the 'search' folders into the library
Some of the new files in my Search Folder belong to existing TV series in my Media Library, others will be part of new series that don't exist in my Media Library yet.
* If you want TVR ro recognise the new shows, then turn 'Auto-Add' on - looks like you have.
I don't want TV Rename to change the filenames or folder structure of my Media Library.
* That's OK, TVR has a few options to help. TVshows can be in a number of formats (eg: all in the root folder or all in sub folders.)
* You can specify the 'root' folder for each TV show
* You can set the library default for many settings and override them for individual shows. (for example generally show subfolders are in the 'season xx' format, but I have some that are in the 'Series xx' format')
* Movies are a little less easy to do this with, but the 'Bulk-Add' feature should take this into account.
I'm aware my library has some minor naming inconsistencies, but these do not cause problems for Kodi's scraper and if I change the filenames or folder structure I will lose the 'watched' status of these files in Kodi. (I have over 1000 TV series and 3000 movies, so going through these manually to mark which have been watched is a non-starter.)
* I have TVR update episode names and folders and Kodi is clever enough to keep track of watched status I think. Maybe do a trial and see.
* TV Rename will suggest changes to keep the library in order, but each suggestion can be ignored.
I set up the folders and preferences as suggested in the Quick-Start. Then when I first ran a Full Scan, I saw suggestions for missing episodes and files that needed renaming in my Media Library, but I couldn't see the downloaded files in my Search Folder.
* They should have been in there? maybe just lost in the noise? Try scaning one show only and may be easier to see.
I found some useful options in Preferences | Scan Settings which turned off features I didn't need such as missing episodes, but now when I run a Full Scan I get no results at all.
* Turnign off missing episodes will really hamper the functionality; I'd leave that on for now.
* If you have a legacy show that needs to stay as it is. Say 'Friends' then it can be ignored per series
* If you have a show where you only want to have seasons 1 and 2 then add not interested seasons to the 'Ignored Seasons' list
* If you have episodes you know you don't care about then you can right click and add the 'missing item' into the 'ignore list' so they don't bug you again
In other news:
There is a 'Quick Rename' function in the tools menu that allows you to quickly dump files there and rename them in place
Under 'Files and Folders' disable 'Case Sensitive match for filenames' as this may reduce minor naming changes
Hope that helps.