Hi, newbie on kdenlive here.

I've very different video sources to use for a video project, different frame-rates (25,29.970,30,50) and resolutions (1080p,720p,640*352).

What frame-rate should I use best for my project?

Can kdenlive handle and convert the different video frame-rates & resolutions without problem or should I unify them first externally?

Thanks in advance!

Set the project settings as you like to render out the video on the end. In your case I would suggest 1080p. Kdenlive will adapt all clips as needed.

If you have clips with variable frame rates you have to convert them (right click on the clip in the project bin -> transcode -> remux with MKV).

You are better off setting the same resolution and frame rate initially so that the final project is of high quality. Some applications convert files to the same format, but there are often some problems. I recommend leaving the resolution at 1080p and the frame rate at 30. I think this is the best option for a video format. I rarely edit videos. Most of the time, I edit photos. Sometimes on shoots, my clients ask me to make a short video backstage from the shoot. Each client gets a flash drive with the processed photos. I also choose the best photo from the shoot and order the framing at https://www.theframeroom.com/. Such a gift makes my clients happy, and that's the most important thing.