All very good questions! We have a vision for what our developer handoff is going to look like, and we're working on getting this up and running for you. In the short term, your devs can install XD and use our measurement tools (Learn to draw simple lines and shapes using the drawing tools in Adobe Experience Design).
However, in the long term, you'll want to rely on our developer handoff workflow, which you can upvote here on UserVoice: Generate specs / measurements / style guide for developers – Adobe XD Feedback : Feature Requests & Bugs
We also shared a vision for what this might look like, so check out this presentation from MAX this past November: Adobe MAX 2016. Day 1 Keynote (Chapter 3) | Adobe Creative Cloud - YouTube (start around minute 24).
Hope that helps!
We’re pleased to announce that our Design Specs feature is now available as a Beta in our November release. You can read more about it :Feature summary | October and November 2017 releases of Adobe XD
This is only a start and we are working on enhancing Design Specs.
We’re looking for your feedback on the feature.
With design specs now you can achieve the below points which was your concern: You can refer to the blog for more info: November Update of Adobe XD | Creative Cloud blog by Adobe
2. Element dimension and distance measurements
3. Color codes of all elements
4. Font type, size, and color of text elements
1. Asset distribution/extraction is not yet rolled out but planned for our future release.
Stay tuned for more updates!