Damn you and your science.
* To see if we've really been turned into women (from XY to XX), or if something else is going on (like we went from XY to XXY or X-).
Looking in the nuclei of each of the blood cell samples, it's apparent that the y-chromosomes of each cell have been subtly altered so that each has grown to an x-chromosome containing the usual information this entails. However, the growth is visibly different to the original genetic material, and thus easily distinguished from the newly-formed x chromosomal material.
* If we do have new X chromosomes, if they're identical to our existing X chromosomes, if the Y was 'stretched' into a new X, or something else.
See above.
* Any trace of residual radiation common to all samples which would be from the weapon, which could lead to figuring out how it was done.
Low frequency radiation of some form just outside the electromagnetic spectrum appears to emit from the newly-formed material. This radiation seems to pass harmlessly through all tissue except for any cells still containing a y-chromosome, where it seems to be absorbed into the chromosome forcing it to grow the additional x-section. Curiously, in Geckolass's blood, her cells seem to attack the newly-formed material, only for the radiation to immediately trigger a regrowth. A quick scan would indicate this frequency to be emitted from some point to the south, but an exact location could not be gleaned. Any radiation passing outwith the samples seems to slowly dissipate.
If anyone else's blood or urine would have distinctive radiation or some other complicating feature, feel free to make up some technobabble.