Free agency starts July 1st. Players can sign with teams starting July 3rd? Or maybe it is the 4th.
The Pistons can make trades right now but it has some rules. They can only trade with other teams whose season is over. So as teams get bounced from the playoffs, they are now eligible to make trades. They can not trade players about to be free agents. They can't trade players who have player/team options this summer.
When the Finals end then all player movement is frozen until July.
I think I read they will have around $26M in cap space. Not sure if that includes the 1st round pick or not. 1st round picks count against the cap from the second they are picked, even if they are not signed.