Does this (conference) mean they need 4 Justices to go to a full hearing/trial?
The Supreme Court is an appellate court. It does not conduct trials. If four Justices vote to hear the case, they will set a schedule for briefs to be filed and oral argument to be held. However, I expect the petition to hear the case to be denied 0-9.
Yes the conference involves all 9, and at least 4 have to vote for the issue to be heard by the court.
IMHO it will come before the full court.
All 9 see their place in history.