I delete it to replace it with the new one. A lot of users play around with the Optional mods folder, so resetting it makes it all available again after updating. Basically resetting the pack state to a known good means that existing optional mods are removed from the game, so need to restore the optional mods folder to allow the user to install it all over again.
This all is a gigantic exercise in addressing all scenarios for all users as best as can be done, so I'm taking into account normal changes users do to the pack after extracting it, like messing with the optional mods folder and adding or removing mods, sometimes to not great results
As a result from this approach, using the updater may also be used to repair your game if you've made a mistake on the plugin front, quickly restoring the plugin state to a known good without needing to download the whole pack again.
About rotation point, yes there are keyboard shortcuts, don't remember them at the top of my head, especially as I'm using 3 keyboard layouts, so kinda just press around till I get what I want
and as for interacting, I don't believe so, I haven't seen such a thing documented nor discussed, and I don't believe I've triggered such a thing during testing.