My steam copy of TDU2 ran an update before starting the game was 1.07gb or so.
Thanks for that confirmation! Sound like the same thing, and same sized update(s) as the non-Steam version -- thus explaining the lack of an update history on steam.
You're fine, as long as you revoked your activations. It's quite possible that the uninstaller does that automatically. (I'm assuming it has a revoke tool or function. Most Securom games do, though some are more of a hassle than others.)
Standard SecuROM. There is a revoke tool. I think I've read it auto revokes on uninstall, as well.