Does Smart Tags delete/remove my existing tags? Would it mess with my store tags?
Smart Tags does not remove existing tags from your products
This was designed so that Smart Tags does not interfere with other installed apps, disrupt your existing workflow.
On the flip side, this also means that Smart Tags won't be able to automatically remove/update tags based on price/weight/quantity if the same tag was created by manually or by another app.
To have Smart Tags automatically manage those tags for you, simply remove them from your products.