I don't think there is any detailed research that goes into selection of each juror - the juror will fill out a Q&A sheet about their family, job, interests, etc., but I don't think either side can go online and look up juror activities. However, if someone was highly interested in the case and denied it, it would be perjury - also once the trial begins the person wouldn't be allowed to discuss it at all, so they'd HAVE to stop posting on here (it would be cause for a mistrial).
I don't know the exact FL law, but under federal law/constitutional law, neither the state nor the defense could strike someone just because of gender, race, etc. There was a big case where the Supreme Court held unconstitutional a situation where one side attempted to strike all older mothers, even though the other side then attempted to strike all young single men (the defendant was a young man). They held any consideration of race or gender is an unconstitutional ground. So JB won't be able to try to elminate all mothers, although he could try to elminate nurses or teachers (since occupation isn't a protected characteristic) - but if it just "happened" all the nurses he struck were older women...then there could be a problem.
Sorry this is getting long - but hopefully it helps! Usually you can only strike people who say they are interested, say something that shows they might not be able to be impartial, or their life experience would cause them to be overly sympathetic to one side or another.
