What are those ._ files?
Those are extended attribute files, which OSX uses when the filesystem doesn't support resource forks or extended attributes.  You don't care about them.  (The entry you quoted is a message to the Finder to display a "This file was downloaded at (date).  Downloaded programs may be unsafe.  Do you want to open it?" dialog along with a button which will open Chrome and take you to the page the file was downloaded from.)