Updating High Sierra to Catalina

I currently run High sierra on my skylake i3 cpu and a geforce 750Ti. But Ive come to the point that I dont need my graphics anymore and Would like to update to catalina for latest software.I have a few questions in my minds now 1. Can I simply update from the app store to mojave and then to catalina ? Or a fresh install is better ? 2. Are there any overheads which I need to do with opencore before ? 3. Should I change my VGA output from gfx card to Motherboard output or just keep it like that ?

submitted by /u/MemEG-0-D
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