saguaros thank for your quick reply, however I don't find it very helpful ... It's not a problem for me to run the plugin 10 times, it works blazingly fast considering the amount of data, but I need to be absolutely certain it won't make double imports or skip some items this way. Also, you seem to have missed my question regarding "video" field import, this is also very important, so I would need you to shed some light on this as I can't figure out where and how exactly the plugin moves this data (video provider, video ID). The hyperlink to the documentation I included in my original post says that the plugin imports video fields, so I guess I'm missing something.
Please take your time, no need to hurry, and I'm not being hostile here – I wouldn't be able to do this without the help of your plugin anyway, plus it does 99% of the job "out of the box" – but I really need helpful answers.
Thanks again in advance!