These questions are dropped here by the community to have them answered, and possibly moved into "useful info" or "FAQ", depending of the frequency of occurences. :-)
The Construct is still in flux. Generally the latest version (eg. git pull) works well, but if you want to stay on the safe side you should ask the helpful folks in the #test:zemos.net room.
I don't know but you are strongly advised not to join it from a normal client since everything will start dying trying to serve you with multiple hundred megabytes of JSON on sync, and it's pretty tough to get rid of it since you will not be able to leave it easily.
If you did it you will have to get familiar with room purge * console commands...
