The pages under Limits, Verify and Glossary answer most of it, including the parts that are not built yet. If yours is not there, write — the more exact the error text, the shorter the thread.
Include what you did, what happened, and the browser you used. Never paste a drop link — it carries the key to the files it points at.
The client is readable in full in your browser; what you may and may not do with it is on the read the code page. The changelog is where any change to that shows up first.
Disagreements about the design are more useful than compliments about it. If a claim on this site does not survive your own check, that is the most useful mail we can get.
One address, no routing rules behind it. Pick this if none of the others fit.