Do both lawyers and the judge have to approve of the juror before they can be on a jury?

No.  Both sides have a certain number of peremptory challenges, meaning that they have a certain number of times they can remove a juror at their whim, without needing agreement from the other party or parties, or the judge.  Once those challenges are used up, a juror can only be removed for cause, meaning that a party trying to remove a juror would have to convince the Judge that there was cause to remove the juror.  You would never need the other side's agreement, only the judge's.