I cannot confirm at least one of your points. When it seems that you have lost your character just connect to a different server. Some of them are experimental servers without declaration.
Everything works fine for me.

had the same

1. login new charakter spawn.
2. log off, closed dayz
3. open dayz, log on an different server, and i had my old one.

Thats right, connecting to a different server works. The reason so many ppl have that issue on a server is a different hive. I have connected to a public hardcore server after leaving another one yesterday WITHOUT time penalty and i was a fresh spawn. Left the server immediately and joined another one. No problem.
I dont know what hive this is but its clearly a different one as you can see by the missing time penalty.

I just tried again with todays updated client. i tried 10 regular public servers with players on them. I tried a mix of french, spanish and UK servers, from different hosts. All of them had the same problem - char always reset, no items anywhere.

This is a HUGE issue.

On the last server I tried, I noticed it said something like "your character could not be loaded and is being reset" or similar in red at the bottom.

The game is totally unusable for me since 48 release, and no fix, or acknowledgement of the issue even. I have ment plenty of people in game with exactly the same problem. for me its all servers.

This is not the issue - I know the different Hives. I have a char on the hard core non experimental hive, and a char on the regular not experimental, and a few chars on private hives.
The issue is I can log into any public regular hive, and NEVER see a single item, and the char never saves.
I can log into any of my list of fav servers on teh same hive, and always get a new char every time.
I am an expert at this game - this is a major bug, not a user error.

I too had the same problem yesterday just after the update. I updated the game and decided that I would play some. I joined my regular, Favorited server. Upon logging in, I recognized that I still had my character but it was pitch black and only 3 other people were on the server. So I decided to give another server a try. I found one that had about 25 players and joined. It was a regular, stable server just like my favorite server. Upon logging into this one, I spawned in the NE without any of my loot, I was a freshspawn. I immediately logged out and logged back into my favorite server. I spawned in as a freshspawn again. I tried multiple servers to no avail. Restarted my game, steam, my PC, and nothing. ATM I am looking for solutions as teh character I had has been alive since April and I would hate to lose him.

Same.

Okay a friend of mine has the same problem now. Always character resets sometimes when rejoining the same server after restart.
He tried about 20 times and now the problem is somehow gone

I just tried another 5 random public hive regular non experimental servers. One of them had items! I loged out and in again, and char persisted. Got really excited, so went to a different server, back to a reset char and no loot anywhere. Cant remember the one server in about 40 I have tried which worked. I notice that about half the servers I try say something like "you char could not be loaded from the server and is being reset", but the message goes very quickly. Is NO ONE ELSE getting this?