Yes, they are carried over, however the Snippets panel and how they work has changed.
Keyboard shortcuts have been replaced by a new keyword system and the ability to create wrapping Snippets in inexplicably gone. Learn how to reuse code in Dreamweaver with the Snippets panel
I will be running 2017 in parallel to 2015 for a while (to familiarize myself with the new interface), hoping they fix some of the problems in an early dot release.
When you install, make sure to choose Advanced Options from the first dialogue window that pops up so you can uncheck "Remove Older Versions". You can have CC2015 and CC2017 installed at the same time, they just won't run at the same time.