1. You can patch on desktop. Make sure you have device ID writen down somewhere handy You need to have navcore and map installed on SD aswell, not only map!
2. Your is quite enough, you'll need to patch ttsystem (or PNDNavigator if present) file to allow tt reading cracked maps - you can do it on sd only - safe
3. You can have your current navcore version - no significant benefits to the others, will work properly with all maps.
4. Patch like a map and put all into a map folder.
In short: leave your internal memory as is - you will have legit system+maps. Play only with SD - tt will read SD only when inserted.