Is there any word about whether you will be able to have different saves. 1 For playing on your own. 2. For playing Multiplayer.
You can create 4 characters, so just have a character for each.
Excellent 
but with one caracter i can play alone and join co-op sessions and go back to play alone?
As far as I know, Yes.
also with the stuff i carry with me or is there a limitation?
The stuff that’s with you should stay with you.