>>> Does this leak violate his right to a fair trial by fabricating grounds to disqualify many potential jurors who would be sympathetic to him?

Nope.

This is because during the jury selection process or "voir dire" each side has a set number of "Peremptory Challenges" which either side doesn't need a reason, they just say, "Jury Member #23 - Peremptory Challenge" and they will be removed no questions asked.

The other kind of challenge is called "Challenge for Cause" of which either side has an unlimited number of. This is where one side will challenge a juror based on certain criteria like "implied bias" or "actual bias". At this point the attorneys have to present their arguments to the judge and the judge makes the final call on whether the juror will be dismissed or kept.

Once each side has exhausted both sets of challenges, you normally have enough people to fill a jury with several alternates.

Because of how fair the process is it means the odds of getting people who are sympathetic to him have an equal chance of getting on the jury, just as there are of getting people who think hackers are the worst people on the planet. This is why its such a chess match. Each side is trying to get enough jurors to sympathize with their client, or the tip the balance in their favor based on the questions they are allowed to ask in order to uncover any kind of bias, or certain beliefs they have which would make an attorney think they will likely support their client and see him as innocent.

>>> If it doesn't (which seems probable), would a severe enough leak of this kind do the above?

Not until after the jury has been set.

Then the judge has to determine if there are enough leaks, and how damaging to the trial they will be. The judge can also sequester a jury which means they won't get any news of the case. Remember how awful the leaks were in the OJ Simpson case? Judge Ito knew it was going to be a circus and sequestered the jury right away. The paper the jurors got each day had all the OJ stories cut out, and they weren't allowed to have a tv or magazines or anything which would inform them about what was going on outside the courthouse with the case. They just moved between the courthouse and their hotel where they were staying the entire trial.

Of course you can also opt for a change of venue before a trial starts and before jury selection to try and get a jury better suited for your client. Some of the more high profile cases where this has happened:

1 - Rodney King Case. The appeals court granted a change in venue from LA to the neighboring Simi Valley because of the "saturated media". Simi Valley just happened to be an affluent white community. Is it any wonder the cops were acquitted in record time??

2 - Oklahoma City Bombing - The attorneys for Timothy McVeigh successfully argued for a change of venue because they felt there was a substantial prejudice in OK City against McVeigh and felt there was no way he would get a fair and impartial trial. It was granted because of the amount of coverage and the stories in the press "demonized" both defendants. The venue was changed to Denver Colorado. McVeigh was still found guilty despite the change of venue.

3 - Boston Marathon Bomber - A judge recently denied a change of venue to Dzhokhar Tsarnaev saying the although the media attention was significant and ongoing, but said Tsarnaev's defense attorney's failed to prove how it would prejudice a fair and impartial jury. His trial is set to start in Sept. of 2015.