Some years ago I changed from Lightroom to Capture One and I'm really happy with this.
My question now: Can I use the whole functionality from LRT5 together with Capture One respectively what's the issues/limitations ?

LRTimelapse uses the Adobe XMP workflow and Adobe Raw Converter for all the develop tasks.
So no, it's not possible to use it witch Capture One or any other Raw converter.
The new LRTimelapse 6 brings a simple workflow, which doesn't require Lightroom, but it's limited. Please see my announcement video linked on the download page: https://lrtimelapse.com/download/