Hi @stratus,
Yes, you should be able to simultaneusly obtain both the Gaze Data and Fixation Data Stream using the Tobii Core SDK which provides further enchancements over the now deprecated EyeX SDK but with an almost identical syntax.
In addtion, we have included a number of detailed sample projects to help you get up and running @ https://github.com/Tobii/CoreSDK
which include several methods on obtaining data streams including fixation and gaze that should be exactly what you are looking for!
In terms of Eye Tracker Frequency, bear in mind that with the Tobii C4 Eye Tracker that Capture Rate does fluctuate around an average value of around 90Hz.
Should your development necessitate an eye tracker with a more precise sample rate (or indeed if you intend to store gaze data for scientific use) then I would refer you to the Tobii Pro range of Trackers and software. In the meantime, check out the aforementioned Core SDK samples and please let us know how you get on.